Signal transmission cable and communication device module

ABSTRACT

A signal transmission cable including a high-Q value band-elimination filter includes a first signal line conductor pattern including a first capacitor conductor portion and an inductor conductor portion on a first base layer. The first capacitor conductor portion includes a flat conductor, and the inductor conductor portion has a spiral shape. A second signal line conductor pattern including a second capacitor conductor portion is provided on a second base layer. The inductor conductor portion constitutes an inductor, and the first and second capacitor conductor portions and the first base layer constitute a capacitor. The inductor and the capacitor are connected in parallel by transmission conductor portions on the first and second base layers and an interlayer-connector conductor on the first base layer.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to signal transmission cables thatpreferably define and function as a band-elimination filter and/or asignal transmission line connecting two circuits.

2. Description of the Related Art

In the related art, some small electronic devices performing wirelesscommunications such as cellular phones and the like include a pluralityof mount-type components such as boards and the like in their casings.In such a case, the plurality of boards is sometimes connected byflexible flat cables.

For example, a small electronic device performing wirelesscommunications includes an antenna board and a front end board (refer toPCT International Publication No. WO 2005/114778 A1). On the antennaboard, an antenna is formed for transmitting and receivinghigh-frequency signals. On the front end board, a front end circuit isformed. The front end circuit generates high-frequency signals to beradiated from the antenna, and amplifies and demodulates high-frequencysignals received with the antenna. The antenna board and the front endboard are generally placed at locations separated from each other in thecasing. Thus, a flat cable is used to connect the antenna board and thefront end board.

Further, in current small electronic devices, the antenna is configuredto be able to transmit and receive high-frequency signals in a pluralityof communication bands, and shared by front end circuits of respectivecommunication bands. Thus, a high-frequency filter is typicallyconnected between the antenna and each front end circuit to establishisolation between the front end circuits of the respective communicationbands.

Further, in small electronic devices of the related art, such ahigh-frequency filter is mounted or formed on the front end board onwhich the front end circuit is formed. In a case where thehigh-frequency filter is mounted on the front end board, an inductor anda capacitor constituting the high-frequency filter are mount-typeelements, as is the case with an inductor element described in JapaneseUnexamined Patent Application Publication No. 2000-196391, for example.In a case where a high-frequency filter is formed on the front endboard, an inductor and a capacitor constituting the high-frequencyfilter are realized with inner layer electrode patterns in the front endboard.

However, in the foregoing related art configuration, the high-frequencyfilter is formed on the front end board. As a result, a shape of thefront end board becomes larger by the volume of the high-frequencyfilter thus formed. This put a limitation on downsizing of the front endboard.

Further, when an attempt is made to downsize the high-frequency filtermounted or formed on the front end board, the line width of the inductoris reduced, or constraints are imposed on the shape of the inductor.This degrades the Q value of the inductor, and accordingly degrades theQ value of the high-frequency filter. Accordingly, in some cases,desired filter characteristics (bandpass characteristic or attenuationcharacteristic) may not be achieved. For example, in a case where aband-elimination filter is formed, a steep attenuation characteristiccannot be achieved.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide a signaltransmission cable including a high-Q value band-elimination filter.

A signal transmission cable according to a preferred embodiment of thepresent invention includes a signal transmission line, a base body, anda band-elimination filter. The signal transmission line connects a firstexternal connection terminal and a second external connection terminal.The base body is a flexible flat member in which the signal transmissionline is defined by a conductor pattern. The band-elimination filter isconnected between the first external connection terminal and the secondexternal connection terminal by the signal transmission line, andincludes an inductor and a capacitor provided in or on the flexible flatbase body.

In this configuration, the band-elimination filter is provided withinthe signal transmission cable. Thus, a high-frequency signal inputtedfrom the first external connection terminal is outputted to the secondexternal connection terminal after a specific frequency band isattenuated by the band-elimination filter. This eliminates the need of aband-elimination filter in two external circuit boards to be connectedby the signal transmission cable. Further, compared with mount-typecomponents, a larger area is available to provide an inductor, andflexibility in inductor designing is improved. Thus, a high-Q valueinductor is able to be fabricated easily compared with mount-typecomponents. This facilitates realization of a signal transmission cableincluding a high-Q value band-elimination filter.

Further, preferably, the signal transmission cable according to apreferred embodiment of the present invention has a followingconfiguration. The base body includes a multilayer structure including astack of a plurality of base layers. The inductor includes a lineconductor pattern located on at least one layer of the plurality of baselayers. The inductor and the capacitor are connected in parallel by theconductor pattern.

This configuration defines specific configuration examples of theinductor and the band-elimination filter including that inductor.Providing a planar inductor on the base body makes it possible tosignificantly reduce or prevent an increase in the thickness of the basebody due to the formation of the inductor.

Further, preferably, in the signal transmission cable according to apreferred embodiment of the present invention, the capacitor includesflat conductor patterns provided on the plurality of base layers, theflat conductor patterns opposing each other in a stacking direction ofthe multilayer structure.

In this configuration, the capacitor is also provided inside the basebody. Thus, the thickness of the signal transmission cable issignificantly reduced.

Further, in the signal transmission cable according to a preferredembodiment of the present invention, the capacitor may be a surfacemount element, and this surface mount element may be mounted at alocation where the signal transmission line is cut in such a way thatthe surface mount element is connected in series between separatedsignal transmission lines.

This configuration makes it possible to have a large capacitance thatcannot be achieved with a capacitor composed of flat conductor patternsformed inside the base body.

Further, preferably, the signal transmission cable according to apreferred embodiment of the present invention further includes a seriesresonance inductor that includes a line conductor pattern provided onthe plurality of base layers and is connected in series to thecapacitor.

This configuration makes it possible to attenuate a specific frequencyband while reducing transmission loss at a second specific frequencyband that is different from the specific frequency band.

Further, the signal transmission cable with band-elimination filterfunctionality according to a preferred embodiment of the presentinvention may have a following configuration. In each base layer, afirst line conductor pattern constituting the inductor and a second lineconductor pattern constituting the series resonance inductor areprovided. The first line conductor patterns provided at the respectivelayers are connected by an interlayer-connector conductor, and thesecond line conductor patterns provided at the respective layers areconnected by an interlayer-connector conductor that is different fromthe first line conductor patterns.

The second line conductor pattern is divided into a first portionconnecting to the first external connection terminal and a secondportion connecting to the second external connection terminal, and thefirst portion of the second line conductor pattern provided on a firstbase layer and the second portion of the second line conductor patternprovided on a second base layer are arranged opposite to each other overthe base layer.

This configuration enables the formation of the inductor and the seriesresonance inductor using substantially the whole section of the basebody and reduction of the direct-current resistances of the inductor andthe series resonance inductor. Further, this configuration enables theformation of the capacitor using the conductor patterns that constitutethe series resonance inductor. This makes it possible to downsize aband-elimination filter including an LC parallel resonance circuit andthe series resonance inductor to which a capacitor of the LC parallelresonance circuit is connected in series.

Further, the signal transmission cable with band-elimination filterfunctionality according to a preferred embodiment of the presentinvention may have a following configuration. The first line conductorpattern and the second line conductor pattern are provided on three baselayers or more, and a plurality of opposing portions of the firstportion and the second portion are provided.

This configuration achieves further reduction of the direct-currentresistances of the inductor and the series resonance inductor, andwidening of an achievable capacitance range of the capacitor.

Further, the signal transmission cable with band-elimination filterfunctionality according to a preferred embodiment of the presentinvention may have a following configuration. The inductor includes afirst spiral conductor pattern including line conductor patterns and aninterlayer-connector conductor connecting the line conductor patterns,each line conductor pattern being provided on a respective layer of aplurality of the base layers and having a loop-shaped portion of whichis cut off. The series resonance inductor includes a second spiralconductor pattern including line conductor patterns and aninterlayer-connector conductor connecting the line conductor patterns,each line conductor pattern being provided on a respective layer of aplurality of the base layers that is different from the plurality ofbase layers at which the inductor is provided and including aloop-shaped portion of which is cut off.

In this configuration, the inductor and the series resonance inductorare defined by the spiral conductor patterns. This makes it possible torealize an inductor and a series resonance inductor having higher Qvalues compared with other inductor and series resonance inductor havingdifferent shapes.

Further, in the signal transmission cable with band-elimination filterfunctionality according to a preferred embodiment of the presentinvention, a winding direction of the first spiral conductor pattern maybe opposite to a winding direction of the second spiral conductorpattern.

Further, preferably, in the signal transmission cable according to apreferred embodiment of the present invention, the flexible flat basebody includes liquid crystal polymer. In this configuration, a materialhaving a low tan δ is used for the base body. Thus, the transmissionloss of signal transmission line is significantly reduced. Further, theparasitic capacitance of the inductor becomes smaller, and aband-elimination filter having a still higher Q value is provided.

Further, preferably, in the signal transmission cable according to apreferred embodiment of the present invention, the flexible flat basebody includes a bent portion between a position of the first externalconnection terminal and a position of the second external connectionterminal. This configuration makes it possible to improve flexibility inarranging a first external circuit board to be connected with the firstexternal connection terminal and a second external circuit board to beconnected with the second external connection terminal.

Further, in the signal transmission cable according to a preferredembodiment of the present invention, the first external connectionterminal and the second external connection terminal may each include aconnector member that establishes an electrical connection with anexternal circuit by connecting each other mechanically. Thisconfiguration defines specific structures of the first and secondexternal connection terminals. This configuration facilitates connectingand fixing of the first and second external connection terminals to theexternal circuit boards.

A signal transmission cable with diplexer functionality according to apreferred embodiment of the present invention includes the signaltransmission cable with band-elimination filter functionality accordingto one of the preferred embodiments of the present invention describedabove and a bandpass filter including other conductor patterns providedin the flexible flat base body.

This configuration enables the formation of a thin diplexer havingexcellent transmission characteristics.

Further, a communication device module according to a preferredembodiment of the present invention includes one of the signaltransmission cables, an antenna board connected to the first externalconnection terminal, and a front end board connected to the secondexternal connection terminal. Further, a communication module accordingto a preferred embodiment of the present invention includes the signaltransmission cable with diplexer functionality, and an antenna board anda front end board that are connected by this signal transmission cablewith diplexer functionality.

With these configurations, small communication device modules havingexcellent communication characteristics are realized by including thesignal transmission cable.

According to preferred embodiments of the present invention, the signaltransmission cables including high-Q value band-elimination filters arerealized. This makes it possible to significantly downsize communicationdevice modules without degrading transmission and receptioncharacteristics.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an external perspective view of a signal transmission cableaccording to a first preferred embodiment of the present invention.

FIG. 2 is an exploded perspective view of a signal transmission cableaccording to the first preferred embodiment of the present invention.

FIG. 3A and FIG. 3B are plan views of conductor patterns in respectivebase layers of a signal transmission cable according to the firstpreferred embodiment of the present invention.

FIG. 4 is an equivalent circuit diagram of a signal transmission cableaccording to the first preferred embodiment of the present invention.

FIG. 5 is a graph depicting bandpass characteristic of a signaltransmission cable according to the first preferred embodiment of thepresent invention and bandpass characteristic of a combined structure ofa signal transmission cable of related art and a band-elimination filterelement.

FIG. 6 is an exploded perspective view of a signal transmission cableaccording to a second preferred embodiment of the present invention.

FIG. 7A and FIG. 7B are plan views of conductor patterns in respectivebase layers of a signal transmission cable according to the secondpreferred embodiment of the present invention.

FIG. 8 is an exploded perspective view of a signal transmission cableaccording to a third preferred embodiment of the present invention.

FIG. 9 is an exploded perspective view of a signal transmission cableaccording to a fourth preferred embodiment of the present invention.

FIG. 10 is an exploded perspective view of a signal transmission cableaccording to a fifth preferred embodiment of the present invention.

FIG. 11 is an exploded perspective view of a signal transmission cableaccording to a sixth preferred embodiment of the present invention.

FIG. 12A and FIG. 12B are cross-sectional views for describing a mountstructure of a surface mount capacitor element.

FIG. 13 is an exploded perspective view of a signal transmission cableaccording to a seventh preferred embodiment of the present invention.

FIG. 14 is an equivalent circuit diagram of a signal transmission cableaccording to the seventh preferred embodiment of the present invention.

FIG. 15 is a graph depicting bandpass characteristic of a signaltransmission cable according to the seventh preferred embodiment of thepresent invention and bandpass characteristic of a combined structure ofthe signal transmission cable of the third preferred embodiment and aband-elimination filter element.

FIG. 16 is an exploded perspective view of a signal transmission cableaccording to an eighth preferred embodiment of the present invention.

FIG. 17 is plan views of conductor patterns in respective base layers ofa signal transmission cable according to the eighth preferred embodimentof the present invention.

FIG. 18 is an equivalent circuit diagram of a signal transmission cableaccording to the eighth preferred embodiment of the present invention.

FIG. 19 is an exploded perspective view of a signal transmission cableaccording to a ninth preferred embodiment of the present invention.

FIG. 20 is an exploded perspective view of a signal transmission cableaccording to a tenth preferred embodiment of the present invention.

FIG. 21 is plan views of conductor patterns in respective base layers ofa signal transmission cable according to the tenth preferred embodimentof the present invention.

FIG. 22 is an equivalent circuit diagram of a signal transmission cableaccording to the tenth preferred embodiment of the present invention.

FIG. 23 is an exploded perspective view of a signal transmission cableaccording to an eleventh preferred embodiment of the present invention.

FIG. 24 is plan views of conductor patterns in respective base layers ofa signal transmission cable according to a twelfth preferred embodimentof the present invention.

FIG. 25 is a graph depicting bandpass characteristics of the signaltransmission cables according to the tenth and twelfth preferredembodiments of the present invention.

FIG. 26 is an exploded perspective view of a signal transmission cableaccording to a thirteenth preferred embodiment of the present invention.

FIG. 27 is a block diagram of a communication device module according toone preferred embodiment of the present invention.

FIG. 28 is a side view depicting a schematic configuration of acommunication device module according to a preferred embodiment of thepresent invention.

FIG. 29 is an exploded perspective view of a diplexer-type signaltransmission cable according to a fourteenth preferred embodiment of thepresent invention.

FIG. 30 is a graph depicting transmission characteristics of adiplexer-type signal transmission cable according to the fourteenthpreferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A signal transmission cable according to a first preferred embodiment ofthe present invention is described with reference to the drawings. FIG.1 is an external perspective view of a signal transmission cableaccording to the first preferred embodiment of the present invention.FIG. 2 is an exploded perspective view of the signal transmission cableaccording to the first preferred embodiment of the present invention.FIG. 3A and FIG. 3B are plan views of conductor patterns in respectivebase layers of the signal transmission cable according to the firstpreferred embodiment of the present invention. In the following section,to view the signal transmission cable (base body and base layers) in adirection orthogonal to a first direction and a second direction isreferred to as “to view in planar view”.

As depicted in FIG. 1, a signal transmission cable 10 includes a flatbase body 100 extending in two directions, the first direction and thesecond direction. The length of the base body 100 in the first directionis determined based on a distance between connecting locations of twoexternal circuit boards to be connected by this signal transmissioncable 10. The length of the base body 100 in the second direction isdetermined based on shapes of inductors or capacitors provided insidethe base body 100, which will be described below. The thickness of thebase body 100 may be arbitrarily determined, and is about 0.2 mm to 0.5mm, for example. An insulating resist film 110 is provided on one offlat surfaces (surfaces parallel to the first direction and the seconddirection) of the base body 100 so as to cover substantially the entirearea thereof.

The base body 100 is formed preferably by stacking a base layer 101 anda base layer 102. The base layers 101 and 102 are each composed of aflexible insulating flat film such as, for example, a liquid crystalpolymer. The base layers 101 and 102 are stacked in this order from theresist film 110 side. In other words, the resist film 110 is provided ona flat surface of the base layer 101 opposite to the base layer 102.

A signal line conductor pattern 210 and external connection conductors311 and 312 are provided on the resist film 110 side surface of the baselayer 101. The signal line conductor pattern 210 and the externalconnection conductors 311 and 312 are composed of a metal having highelectrical conductivity and the like, such as a copper foil and thelike.

The external connection conductor 311 is located in the vicinity of anEL11 end portion that is one end portion of the base layer 101 in thefirst direction. The external connection conductor 311 is square orapproximately square in planar view. The external connection conductor312 is located in the vicinity of an EL12 end portion that is the otherend portion of the base layer 101 in the first direction. The externalconnection conductor 312 is square or approximately square in planarview.

As depicted in FIG. 2 and FIG. 3A, the signal line conductor pattern 210includes a transmission conductor portion 211, a capacitor conductorportion 212, and an inductor conductor portion 213.

The transmission conductor portion 211 is a line conductor extending inthe first direction. One end portion of the transmission conductorportion 211 in the extending direction is connected to the externalconnection conductor 311. The other end portion of the transmissionconductor portion 211 in the extending direction is connected to thecapacitor conductor portion 212.

The capacitor conductor portion 212 is a flat conductor, and the lengthof the capacitor conductor portion 212 in the second direction is longerthan the length of the transmission conductor portion 211 in the seconddirection. In other words, the capacitor conductor portion 212 includesa wide-width flat conductor.

The inductor conductor portion 213 includes a line conductor having aspiral shape in planar view. The inductor conductor portion 213 isprovided at substantially the same location as the capacitor conductorportion 212 in the first direction. An outer circumferential side endportion of the spiral shape of the inductor conductor portion 213 isconnected to the capacitor conductor portion 212. For example, the outercircumferential side end portion of the inductor conductor portion 213is connected to substantially the center position of the capacitorconductor portion 212 in the first direction. A center-side end portionof the inductor conductor portion 213 is connected to aninterlayer-connector conductor 401.

The base layer 101 includes the interlayer-connector conductors 401 and402. The interlayer-connector conductor 401 and 402 are formedpreferably by filling through-holes that penetrates the base layer 101with electrically conductive paste and solidifying them. Theelectrically conductive paste includes an electrically conductivematerial whose primary component is silver or tin.

The interlayer-connector conductor 401 is provided at the location ofthe center-side end portion of the inductor conductor portion 213. Theinterlayer-connector conductor 402 is provided inside a formation regionof the external connection conductor 312.

A signal line conductor pattern 220 is provided on the base layer 101side surface of the base layer 102. As is the case with the signal lineconductor pattern 210, the signal line conductor pattern 220 includes ametal having high electrical conductivity and the like, such as a copperfoil and the like.

As depicted in FIG. 2 and FIG. 3B, the signal line conductor pattern 220includes a capacitor conductor portion 221 and transmission conductorportions 222 and 223.

As is the case with the capacitor conductor portion 212 of the baselayer 101, the capacitor conductor portion 221 includes a wide-widthflat conductor. The capacitor conductor portion 221 faces the capacitorconductor portion 212 over the base layer 101.

The transmission conductor portion 222 is a line conductor extending inthe second direction. One end portion of the transmission conductorportion 222 in the extending direction (end portion on EL21 side) isconnected to the capacitor conductor portion 221. The other end portionof the transmission conductor portion 222 in the extending direction(end portion on EL22 side) is connected to the interlayer-connectorconductor 401.

The transmission conductor portion 223 is a line conductor extending inthe first direction, and one end portion of the transmission conductorportion 223 in the extending direction (end portion on EL11 side) isconnected to the capacitor conductor portion 221. The other end portionof the transmission conductor portion 223 in the extending direction(end portion on EL12 side) is connected to the interlayer-connectorconductor 402.

Connectors 501 and 502 are provided on the resist film 110 side of thebase body 100. The connectors 501 and 502 each has a structure thatestablishes electrical connection between a circuit of an external boardand the signal transmission cable 10 by physically connecting theconnector to a connector mount portion of an external circuit board,which is not illustrated in the drawings. The connectors 501 and 502 maybe omitted. However, the use of the connectors 501 and 502 makes itpossible to improve reliability of connections between the signaltransmission cable 10 and first and second external circuit boards.

The connector 501 is disposed at an opening 111 provided on the resistfilm 110 and mounted on the external connection conductor 311. Acombination of these elements corresponds to a first external connectionterminal. The connector 502 is arranged at an opening 112 in the resistfilm 110 and mounted on the external connection conductor 312. Acombination of these elements corresponds to a second externalconnection terminal.

According to the foregoing configuration, a high-frequency signalinputted from a first external circuit board via the connector 501 istransmitted through the external connection conductor 311, the signalline conductor pattern 210, the signal line conductor pattern 220, andthe external connection conductor 312, and outputted to a secondexternal circuit board via the connector 502. More precisely speaking,the high-frequency signals travel the interlayer-connector conductors401 and 402. These elements are included in the signal line conductorpatterns that constitute a signal transmission line.

Further, using the configuration of the present preferred embodimentmakes it possible to realize a band-elimination filter circuit whoseequivalent circuit is depicted in FIG. 4. FIG. 4 is an equivalentcircuit diagram of a signal transmission cable according to the firstpreferred embodiment of the present invention.

As depicted in FIG. 4, the signal transmission cable of the presentpreferred embodiment has a circuit configuration in which a parallelcircuit of an inductor L1 and a capacitor C1 is connected between theexternal connection conductors 501 and 502. The inductor L1 is realizedwith the inductor conductor portion 213 having the spiral shape. Thecapacitor C1 is realized with the capacitor conductors 212 and 221opposing each other and the base layer 101 sandwiched between thecapacitor conductors 212 and 221. Lines connecting in parallel theinductor L1 and the capacitor C1 are realized with the transmissionconductor portion 222 and a connecting portion between the inductorconductor portion 213 and the capacitor conductor 212.

As described above, by using the configuration of the present preferredembodiment, the signal transmission cable 10 including an LC parallelresonance circuit is realized. Further, this LC parallel resonancecircuit works as a band-elimination filter whose attenuation polefrequency is set at a desired frequency by adjusting values of elements.In other words, by using the configuration of the present preferredembodiment, a signal transmission cable with band-elimination filterfunctionality is realized.

This makes it possible to provide a small communication device moduleincluding the signal transmission cable 10 without requiring anyadditional mounting of an inductor or a capacitor on an external circuitboard.

Further, in the configuration of the present preferred embodiment, theinductor is preferably provided on the flat surface of the base body 100based on the length of the base body 100 in the second direction.Accordingly, the conductors that constitute the inductor are able to bemade wider in width and larger in size compared with a mount-componenttype inductor mounted on a related art external circuit board. Thisreduces the series resistance of the inductor and improves the Q value.Accordingly, a high-Q value LC parallel resonance circuit, namely, aband-elimination filter with steep attenuation characteristic isrealized.

FIG. 5 is a graph depicting the bandpass characteristic of a signaltransmission cable according to the first preferred embodiment of thepresent invention and the bandpass characteristic of a combinedstructure of a signal transmission cable of related art and aband-elimination filter element. As depicted in FIG. 5, compared with acombination of a signal transmission cable and a mount typeband-elimination filter element of related art, the signal transmissioncable 10 of the present preferred embodiment has a steeper attenuationcharacteristic and achieves a larger level of attenuation than relatedart at attenuation pole frequency f0.

In the present preferred embodiment, an example is described in which aliquid crystal polymer is used for the base layers 101 and 102. However,a different material may alternatively be used as long as the materialis a flexible insulating material. It should be noted that, when aliquid crystal polymer is used, tan δ becomes small, and this reducesthe transmission loss of signal transmission line. Further, this reducesthe parasitic capacitance of inductor becomes smaller, thus realizing aband-elimination filter having a still higher Q value.

The signal transmission cable 10 is fabricated in the following manner.First, the base layers 101 and 102 including copper cladding on one sideare prepared. The signal line conductor pattern 210 and the externalconnection conductors 311 and 312 are formed preferably by performing apatterning process on the copper foil of the base layer 101. Similarly,the signal line conductor pattern 220 is formed preferably by performinga patterning process on the copper foil of the base layer 102.

Next, through-holes are formed on the base layer 101. Thesethrough-holes are formed from the opposite side of the formation surfaceof the signal line conductor pattern 210 and the external connectionconductor 312 using, for example, a laser and the like. Further, thesethrough-holes are filled with an electrically conductive paste.

Subsequently, the base layers 101 and 102 are stacked on top of eachother, and the base layers 101 and 102 thus stacked are then subjectedto thermocompression bonding. During this process, the electricallyconductive paste inside the through-holes is solidified, and theinterlayer-connector conductors 401 and 402 are formed.

Subsequently, the resist film 110 is formed on the base layer 101 sidesurface of the base body 100. The openings 111 and 112 are in the resistfilm 110 at regions that contact the external connection conductors 311and 312. The connector 501 and 502 are mounted by fitting in theopenings 111 and 112 to connect to the external connection conductors311 and 312, respectively.

Next, a signal transmission cable according to the second preferredembodiment of the present invention is described with reference to thedrawings. FIG. 6 is an exploded perspective view of the signaltransmission cable according to the second preferred embodiment of thepresent invention. FIGS. 7A and 7B are plan views of conductor patternsin respective base layers of the signal transmission cable according tothe second preferred embodiment of the present invention. A signaltransmission cable 10A of the present preferred embodiment differs fromthe signal transmission cable 10 according to the first preferredembodiment in that the inductor and the capacitor are arranged along thefirst direction. The same structures are preferably used to install aresist film 110A and connectors 501 and 502, and the description thereofis omitted.

As depicted in FIG. 6, FIG. 7A, and FIG. 7B, a base body 100A of thesignal transmission cable 10A is formed preferably by stacking baselayers 101A and 102A and has an elongated shape extending in the firstdirection.

A signal line conductor pattern 210A and the external connectionconductors 311 and 312 are provided on the resist film 110A side surfaceof the base layer 101A. The external connection conductor 311 is locatedin the vicinity of the EL11 end portion of the base layer 101A, and theexternal connection conductor 312 is located in the vicinity of the EL12end portion of the base layer 101A.

As depicted in FIG. 6 and FIG. 7A, the signal line conductor pattern210A includes transmission conductor portions 211A and 214A, a capacitorconductor portion 212A, and an inductor conductor portion 213A.

The transmission conductor portion 211A is a line conductor extending inthe first direction. One end portion of the transmission conductorportion 211A in the extending direction is connected to the externalconnection conductor 311. The other end portion of the transmissionconductor portion 211A in the extending direction is connected to thecapacitor conductor portion 212A.

The capacitor conductor portion 212A is a flat conductor, and the lengthof the capacitor conductor portion 212A in the second direction islonger than the lengths of the transmission conductor portions 211A and214A in the second direction. In other words, the capacitor conductorportion 212A includes a wide-width flat conductor.

The inductor conductor portion 213A includes a line conductor having aspiral shape in planar view. The inductor conductor portion 213A isformed between the capacitor conductor portion 212A and the externalconnection conductor 312 in the first direction so as to be separatedtherefrom.

An outer circumferential side end portion of the spiral shape of theinductor conductor portion 213A is connected to the capacitor conductorportion 212A via the transmission conductor portion 214A including aline conductor. A center-side end portion of the inductor conductorportion 213A is connected to an interlayer-connector conductor 401A.

The base layer 101A includes interlayer-connector conductors 401A and402A. The interlayer-connector conductor 401A is provided at thelocation of the center-side end portion of the inductor conductorportion 213A. The interlayer-connector conductor 402A is provided insidea formation region of the external connection conductor 312.

A signal line conductor pattern 220A is provided on the base layer 101Aside surface of the base layer 102A. As depicted in FIG. 6 and FIG. 7B,the signal line conductor pattern 220A includes a capacitor conductorportion 221A and a transmission conductor portion 223A.

As is the case with the capacitor conductor portion 212A of the baselayer 101A, the capacitor conductor portion 221A includes a wide-widthflat conductor. The capacitor conductor portion 221A opposes thecapacitor conductor portion 212A over the base layer 101A.

The transmission conductor portion 223A is a line conductor extending inthe first direction, and one end portion of the transmission conductorportion 223A in the extending direction (end portion on EL11 side) isconnected to the capacitor conductor portion 221A. The other end portionof the transmission conductor portion 223A in the extending direction(end portion on EL12 side) is connected to the interlayer-connectorconductor 402A.

Even in such a configuration, as is the case with the first preferredembodiment, a signal transmission cable including a high-Q valueband-elimination filter is realized. Further, in the configuration ofthe present preferred embodiment, the inductor and the capacitor arearranged along the extending direction of the signal transmission cable.Thus, a narrow-width signal transmission cable is provided.

Next, a signal transmission cable according to the third preferredembodiment is described with reference to the drawings. FIG. 8 is anexploded perspective view of the signal transmission cable according tothe third preferred embodiment of the present invention. A signaltransmission cable 10B of the present preferred embodiment differs fromthe signal transmission cable 10A described in the second preferredembodiment in arrangement of the connector 502 on a surface of a basebody 100B. In addition to the above, the signal transmission cable 10Bof the present preferred embodiment differs from the signal transmissioncable 10A described in the second preferred embodiment in formationconfiguration of a signal line conductor pattern 220B on a base layer102B. Thus, only portions different from the signal transmission cable10A described in the second preferred embodiment and relevant sectionsrequiring additional descriptions are described in detail.

The base body 100B includes base layers 101B and 102B. The base layer101B is the same as the base layer 101A, and a signal line conductorpattern 210B is the same as the signal line conductor pattern 210A. Onthe base layer 101B, only the external connection conductor 311 isprovided.

The signal line conductor pattern 220B and the external connectionconductor 322 are provided on the base layer 102B at a surface oppositeto the base layer 101B. The external connection conductor 322 is locatedin the vicinity of the EL12 end portion of the base layer 102B.

As depicted in FIG. 8, the signal line conductor pattern 220B includes acapacitor conductor portion 221B and a transmission conductor portion223B.

As is the case with the capacitor conductor portion 212B of the baselayer 101B, the capacitor conductor portion 221B includes a wide-widthflat conductor. The capacitor conductor portion 221B opposes thecapacitor conductor portion 212B over the base layers 101B and 102B.

The transmission conductor portion 223B is a line conductor extending inthe first direction, and one end portion of the transmission conductorportion 223B in the extending direction (end portion on EL11 side) isconnected to the capacitor conductor portion 221B. The other end portionof the transmission conductor portion 223B in the extending direction(end portion on EL12 side) is connected to the external connectionconductor 322.

An insulating resist film 120B is provided on a flat surface of the baselayer 102B opposite to the base layer 101B so as to cover substantiallythe entire area thereof. The connector 502 is arranged at the opening112 in the resist film 120B and mounted on the external connectionconductor 322. A combination of these elements corresponds to the secondexternal connection terminal.

Even in such a configuration, as is the cases with the first and secondpreferred embodiments, a signal transmission cable including a high-Qvalue band-elimination filter is realized. Further, even in a case wheretwo external circuit boards arranged along the thickness direction areto be connected and their connecting directions are opposite to eachother, using the configuration of the present preferred embodimentenables to connect these two external circuit boards easily.

Next, a signal transmission cable according to the fourth preferredembodiment is described with reference to the drawings. FIG. 9 is anexploded perspective view of the signal transmission cable according tothe fourth preferred embodiment of the present invention. A signaltransmission cable 10C of the present preferred embodiment differs fromthe signal transmission cable 10B described in the third preferredembodiment in configuration of the capacitor. Thus, only portionsdifferent from the signal transmission cable 10B described in the thirdpreferred embodiment and relevant sections requiring additionaldescriptions are described in detail.

A base body 100C is formed preferably by stacking base layers 101C,102C, and 103C in this order. On the base layer 102C, only a signal lineconductor pattern 220C is formed. The signal line conductor pattern 220Cincludes a capacitor conductor portion 221C and a transmission conductorportion 223C. The transmission conductor portion 223C is a lineconductor extending in the first direction, and one end portion of thetransmission conductor portion 223C in the extending direction (endportion on EL11 side) is connected to the capacitor conductor portion221C. The other end portion of the transmission conductor portion 223Cin the extending direction (end portion on EL12 side) is extended closeto the EL12 side end portion and connected to an interlayer-connectorconductor 402C.

An interlayer-connector conductor 403C is located inside formationregions of the external connection conductor 311 in the base layers 101Cand 102C. The interlayer-connector conductor 402C is located close tothe EL12 side end portion of the base layer 102C. Theseinterlayer-connector conductors 402C and 403C have shapes that arecontinuous with the base layer 103C.

A signal line conductor pattern 232C, an external connection auxiliaryconductor 331, and the external connection conductor 332 are provided onthe base layer 103C at a surface opposite to the base layer 102C.

The external connection auxiliary conductor 331 is located in thevicinity of the EL11 end portion of the base layer 102C. The externalconnection auxiliary conductor 331 is connected to theinterlayer-connector conductor 403C. The external connection conductor332 is located in the vicinity of the EL12 end portion of the base layer102C. The external connection conductor 332 is connected to theinterlayer-connector conductor 402C.

The signal line conductor pattern 230C includes a capacitor conductorportion 231C and a transmission conductor portion 232C.

As is the case with the capacitor conductor portion 212C of the baselayer 101C and the capacitor conductor portion 221C of the base layer102C, the capacitor conductor portion 231C includes a wide-width flatconductor. The capacitor conductor portion 231C opposes the capacitorconductor portion 221C over the base layer 103C.

The transmission conductor portion 232C is a line conductor extending inthe first direction, and one end portion of the transmission conductorportion 232C in the extending direction (end portion on EL11 side) isconnected to the external connection auxiliary conductor 331. The otherend portion of the transmission conductor portion 232C in the extendingdirection (end portion on EL12 side) is connected to the capacitorconductor portion 231C.

An insulating resist film 120C is provided on a flat surface of the baselayer 103C opposite to the base layer 102C so as to cover substantiallythe entire area thereof. The connector 502 is arranged at the opening112 in the resist film 120C and mounted on the external connectionconductor 332. A combination of these elements corresponds to the secondexternal connection terminal.

In this configuration, the capacitor conductor portions 212C and 221Care arranged opposite to each other over the base layers 101C and 102C,and the capacitor conductor portions 221C and 231C are arranged oppositeto each other over the base layer 103C. Even with such a configuration,a capacitor is able to be provided, and a larger capacitance is able tobe obtained with the same opposing area as in the foregoing preferredembodiments.

Even with such a configuration, functions and effects similar to thoseof the third preferred embodiment are obtained. Further, using theconfiguration of the present preferred embodiment makes it possible toobtain a larger capacitance and a wider range of frequencies of anattenuation pole.

Next, a signal transmission cable according to the fifth preferredembodiment of the present invention is described with reference to thedrawings. FIG. 10 is an exploded perspective view of the signaltransmission cable according to the fifth preferred embodiment of thepresent invention. A signal transmission cable 10D of the presentpreferred embodiment differs from the signal transmission cable 10Adescribed in the second preferred embodiment in that the inductorincludes two layers. Thus, only portions different from the signaltransmission cable 10A described in the second preferred embodiment andrelevant sections requiring additional descriptions are described indetail.

A base body 100D includes base layers 101D and 102D. On the base layer102D, a signal line conductor pattern 220D is provided. The signal lineconductor pattern 220D includes a capacitor conductor portion 221D, atransmission conductor portion 223D, and an inductor conductor portion224D.

The inductor conductor portion 224D is provided on the base layer 102Dcloser to an EL12 end portion side than the capacitor conductor portion221D in the first direction. The inductor conductor portion 224D isdisposed at the same or substantially the same location as a formationlocation of an inductor conductor portion 213D on the base layer 101D.As is the case with the inductor conductor portion 213D, the inductorconductor portion 224D has a spiral shape. A center-side end portion ofthe inductor conductor portion 224D is connected to a center-side endportion of the inductor conductor portion 213D via aninterlayer-connector conductor 401D. The inductor conductor portion 224Dcontinuously winds in the same direction from the inductor conductorportion 213D.

The transmission conductor portion 223D is a line conductor thatconnects the capacitor conductor portion 221D and aninterlayer-connector conductor 402D disposed near the EL12 end portion.The transmission conductor portion 223D has a shape that goes around aformation region of the inductor conductor portion 224D. Thetransmission conductor portion 223D is connected to an outercircumferential side end portion of the inductor conductor portion 224D.

In this configuration, an inductor of an LC parallel resonance circuitincludes the inductor conductor portions 213D and 224D, which areprovided on the two layers, and the interlayer-connector conductor 401Dconnecting these inductor conductor portions 213D and 224D. Accordingly,an inductor having a still larger inductance is provided.

Even with such a configuration, functions and effects similar to thoseof the second preferred embodiment are obtained. Further, using theconfiguration of the present preferred embodiment makes it possible toobtain a larger inductance and widen a range of frequencies of anattenuation pole.

Next, a signal transmission cable according to the sixth preferredembodiment of the present invention is described with reference to thedrawings. FIG. 11 is an exploded perspective view of the signaltransmission cable according to the sixth preferred embodiment of thepresent invention. A signal transmission cable 10E of the presentpreferred embodiment differs from the signal transmission cable 10Adescribed in the second preferred embodiment in that the capacitor is asurface mount element and this surface mount capacitor is built into abase body 100E. Thus, only portions different from the signaltransmission cable 10A described in the second preferred embodiment andrelevant sections requiring additional descriptions are described indetail.

The base body 100E is formed preferably by stacking base layers 101E,104E, and 102E in this order. No capacitor conductor portion is providedon the base layer 101E.

A signal line conductor pattern 220E is provided on the base layer 102Eat a surface opposite to the base layer 104E. Along with this, a resistfilm 120E is provided on a surface of the base layer 102E opposite tothe base layer 104E so as to cover the entire area thereof. The signalline conductor pattern 220E is a line conductor extending in the firstdirection and separated in the middle. An individual portion of thesignal line conductor pattern 220E on the EL11 end portion side is asignal line conductor pattern 220E1, and an individual portion of thesignal line conductor pattern 220E on the EL12 end portion side is asignal line conductor pattern 220E2. The signal line conductor pattern220E2 is connected to a center-side end portion of an inductor conductorportion 213E via an interlayer-connector conductor 401E.

An end portion of the signal line conductor pattern 220E1 on the EL11end portion side is connected to the external connection conductor 311via an interlayer-connector conductor 403E. An end portion of the signalline conductor pattern 220E1 on the EL12 end portion side is connectedto an interlayer-connector conductor 421E having a shape that penetratesthrough the base layer 102E in the thickness direction. An end portionof the signal line conductor pattern 220E2 on the EL12 end portion sideis connected to the external connection conductor 312 via aninterlayer-connector conductor 402E. An end portion of the signal lineconductor pattern 220E2 on the EL11 end portion side is connected to aninterlayer-connector conductor 422E having a shape that penetratesthrough the base layer 102E in the thickness direction.

A surface mount capacitor element 20 is disposed on the base layer 104Eside surface of the base layer 102E. The capacitor element 20 is mountedin such a way that its external connection terminals at both ends areconnected to the interlayer-connector conductors 421E and 422E.

The base layer 104E has no conductor pattern, and a through-hole 160 isprovided on this base layer 104E. The through-hole 160 is formed so asto include a mounting region of the capacitor element 20 in planar viewof the base body 100E.

Even with such a configuration, functions and effects similar to thoseof the second preferred embodiment are achieved. Further, using theconfiguration of the present preferred embodiment enables to achieve alarge capacitance, which cannot be achieved with a capacitor composed ofconductor patterns inside the base body, with a surface mount capacitorelement. Accordingly, the range of frequencies of an attenuation pole ismade wider.

The surface mount capacitor element 20 is installed inside the base body100E preferably in the following manner. FIG. 12A and FIG. 12B arecross-sectional views for describing a mount structure of the surfacemount capacitor element. FIG. 12A is a view depicting a state beforeperforming thermocompression bonding on the base layer, and FIG. 12B isview depicting a state after the thermocompression bonding.

As depicted in FIG. 12A, the base layer 101E, the base layer 104E, andthe base layer 102E are stacked. On the base layer 101E, the signal lineconductor pattern 210E is formed. On the base layer 102E, the signalline conductor patterns 220E1, 220E2, and the interlayer-connectorconductors 421E, 422E are formed. Specifically, in this state,through-holes filled with an electrically conductive paste, which areprevious configurations of the interlayer-connector conductors 421E and422E, are formed in the base layer 102E. At the same time, the capacitorelement 20 is disposed inside the through-hole 160 formed on the baselayer 104E.

These base layers 101E, 104E, and 102E are subjected tothermocompression bonding to form the base body 100E. At this time, theelectrically conductive paste is solidified to form theinterlayer-connector conductors 421E and 422E. Further, theinterlayer-connector conductors 421E and 422E are electrically andphysically connected to external connection terminals of the capacitorelement 20. Further, the through-hole 160 is filled by fusing the baselayers 101E and 104E, thus fixing the capacitor element 20 with the basebody 100E.

Next, a signal transmission cable according to the seventh preferredembodiment of the present invention is described with reference to thedrawings. FIG. 13 is an exploded perspective view of the signaltransmission cable according to the seventh preferred embodiment of thepresent invention. A signal transmission cable 10F of the presentpreferred embodiment differs from the signal transmission cable 10Bdescribed in the third preferred embodiment in that a series resonanceinductor is connected in series to the capacitor. Thus, only portionsdifferent from the signal transmission cable 10B described in the thirdpreferred embodiment and relevant sections requiring additionaldescriptions are described in detail.

A base body 100F is formed preferably by stacking base layers 101F,102F, and 103F in this order. A signal line conductor pattern 220F isprovided on the base layer 101F side surface of the base layer 102F. Thesignal line conductor pattern 220F includes a capacitor conductorportion 221F, a transmission conductor portion 224F, and an inductorconductor portion 225F. The capacitor conductor portion 221F opposes acapacitor conductor portion 212F over the base layer 101F.

The transmission conductor portion 224F is a line conductor extending inthe first direction, and connects the capacitor conductor portion 221Fand an outer circumferential side end portion of the inductor conductorportion 225F.

The inductor conductor portion 225F includes a line conductor having aspiral shape in planar view. The inductor conductor portion 225F islocated at the same or substantially the same location as an inductorconductor portion 213F of the base layer 101F in the first direction. Acenter-side end portion of the inductor conductor portion 225F isconnected to, via an interlayer-connector conductor 401F, a center-sideend portion of the inductor conductor portion 213F and a signal lineconductor pattern 230F in the base layer 103F, which will be describedbelow.

The signal line conductor pattern 230F and the external connectionconductor 332 are provided on the base layer 103F at a surface oppositeto the base layer 102F. The external connection conductor 332 is locatedin the vicinity of an EL12 end portion of the base layer 103F. Thesignal line conductor pattern 230F includes a line conductor extendingin the first direction. An EL11 side end portion of the signal lineconductor pattern 230F is connected to center-side end portions of theinductor conductor portion 213F and 225F via the interlayer-connectorconductor 401F. An end portion of the signal line conductor pattern 230Fon the EL12 end portion side is connected to the external connectionconductor 332.

Further, using the configuration of the present preferred embodimentmakes it possible to realize a band-elimination filter circuit whoseequivalent circuit is depicted in FIG. 14. FIG. 14 is an equivalentcircuit diagram of the signal transmission cable according to theseventh preferred embodiment of the present invention.

As depicted in FIG. 14, the signal transmission cable 10F of the presentpreferred embodiment has a circuit configuration in which a parallelcircuit is connected between the external connection conductors 501 and502, the parallel circuit including an inductor L1 and a seriesresonance circuit of a capacitor C1 and an inductor L2. The inductor L1is realized with the inductor conductor portion 213F having the spiralshape. The capacitor C1 is realized with the capacitor conductors 212Fand 221F opposing each other and the base layer 101F sandwiched betweenthe capacitor conductors 212F and 221F. The inductor L2 is realized withthe inductor conductor portion 225F having the spiral shape.

Lines connecting in parallel the inductor L1 and the series resonancecircuit of the capacitor C1 and the inductor L2 are realized with theinterlayer-connector conductor 401F and a transmission conductor portion214F that connects the inductor conductor portion 213F and the capacitorconductor 212F.

AS described above, by using the configuration of the present preferredembodiment, the signal transmission cable 10F including an LC parallelresonance circuit, to which an LC series resonance circuit is added, isrealized. Further, this LC parallel resonance circuit works as aband-elimination filter whose attenuation pole frequency is set at adesired frequency by adjusting values of elements. Further, this LCseries resonance circuit works as a bandpass filter that passes adesired frequency band by adjusting values of elements. Setting up thispassband at a frequency band of communication signals desired totransmit enables to realize a band-elimination filter that transmitsdesired communication signals with still less loss and attenuatescommunication signals desired to attenuate.

FIG. 15 is a graph depicting the bandpass characteristic of a signaltransmission cable according to the seventh preferred embodiment of thepresent invention and the bandpass characteristic of a combinedstructure of the signal transmission cable of the third preferredembodiment and a band-elimination filter element. As depicted in FIG.15, compared with the signal transmission cable 10C described in thethird preferred embodiment, the signal transmission cable 10F of thepresent preferred embodiment can reduce bandpass loss at a frequencyband that includes a desired frequency f1 (resonance frequency of the LCseries resonance circuit) on the high frequency band side of theattenuation pole while achieving a comparable attenuation level at theattenuation pole frequency. Further, the width of attenuation band atthe high frequency side of the attenuation pole frequency is madenarrower.

In the configuration of the present preferred embodiment, the windingdirection of the inductor conductor portion 213F and the windingdirection of the inductor conductor portion 225F are opposite to eachother in planar view. However, the inductor conductor portion 213F andthe inductor conductor portion 225F may have the same winding direction.These may be arbitrarily determined, for example, based on requiredfilter characteristics.

Next, a signal transmission cable according to the eighth preferredembodiment of the present invention is described with reference to thedrawings. FIG. 16 is an exploded perspective view of the signaltransmission cable according to the eighth preferred embodiment of thepresent invention. FIG. 17 is plan views of conductor patterns inrespective base layers of the signal transmission cable according to theeighth preferred embodiment of the present invention.

As depicted in FIG. 16 and FIG. 17, a signal transmission cable 10Gincludes a flat base body 100G extending in two directions, the firstdirection and the second direction. The thickness of the base body 100Gmay be arbitrarily determined, and preferably is about 0.2 mm to 0.5 mm,for example. An insulating resist film 110G is provided on one of flatsurfaces (surfaces parallel to the first direction and the seconddirection) of the base body 100G so as to cover substantially the entirearea thereof.

The base body 100G is formed preferably by stacking a base layer 101Gand a base layer 102G. The base layers 101G and 102G are each composedof a flexible insulating flat film such as, for example, a liquidcrystal polymer. The base layers 101G and 102G are stacked in this orderfrom the resist film 110G side. In other words, the resist film 110G isprovided on a flat surface of the base layer 101G opposite to the baselayer 102G.

A signal line conductor pattern 610 (hereinafter, simply referred to as“conductor pattern 610”) is provided on the resist film 110G sidesurface of the base layer 101G. The conductor pattern 610 includes ametal having high electrical conductivity and the like, such as a copperfoil and the like. The conductor pattern 610 includes a first conductorportion 611, a second conductor portion 612, a third conductor portion613, a fourth conductor portion 614, and a fifth conductor portion 615.

The first conductor portion 611 and the second conductor portion 612each includes a line conductor extending in the second direction. Thefirst conductor portion 611 and the second conductor portion 612 haveshapes extending substantially the whole length of the base layer 101Gfrom an EL21 side end portion to an EL22 side end portion. The firstconductor portion 611 is located in the vicinity of an EL11 side endportion of the base layer 101G, and the second conductor portion 612 islocated in the vicinity of an EL12 side end portion of the base layer101G.

The third conductor portion 613, the fourth conductor portion 614, andthe fifth conductor portion 615 each includes a line conductor extendingin the first direction. The widths (length in the second direction) ofthe fourth conductor portion 614 and the fifth conductor portion 615 arewider than the width of the third conductor portion 613.

The third conductor portion 613 is located in the vicinity of the EL22side end portion of the base layer 101G. The third conductor portion 613has a shape extending substantially the whole length of the base layer101G from the EL11 side end portion to the EL12 side end portion. TheEL11 side end portion of the third conductor portion 613 is connected tothe first conductor portion 611. The EL12 side end portion of the thirdconductor portion 613 is connected to the second conductor portion 612.

The fourth conductor portion 614 and the fifth conductor portion 615 arelocated in the vicinity of the EL21 side end portion of the base layer101G. The fourth conductor portion 614 has a shape extending from theEL11 side end portion of the base layer 101G to a middle location in thefirst direction. The EL11 side end portion of the fourth conductorportion 614 is connected to the EL21 side end portion of the firstconductor portion 611. The fifth conductor portion 615 has a shapeextending from the EL12 side end portion of the base layer 101G to amiddle location in the first direction. The EL12 side end portion of thefifth conductor portion 615 is connected to the EL21 side end portion ofthe second conductor portion 612. An end portion of the fourth conductorportion 614 opposite to the side connecting to the first conductorportion 611 and an end portion of the fifth conductor portion 615opposite to the side connecting to the second conductor portion 612 arenot connected and are separated from each other. The length of thefourth conductor portion 614 in the first direction is longer than thelength of the fifth conductor portion 615 in the first direction.

A signal line conductor pattern 620 (hereinafter, simply referred to as“conductor pattern 620”) is provided on the base layer 101G side surfaceof the base layer 102G. The conductor pattern 620 includes a metalhaving high electrical conductivity and the like, such as a copper foiland the like. The conductor pattern 620 includes a first conductorportion 621, a second conductor portion 622, a third conductor portion623, a fourth conductor portion 624, and a fifth conductor portion 625.

The first conductor portion 621 and the second conductor portion 622each includes a line conductor extending in the second direction. Thefirst conductor portion 621 and the second conductor portion 622 haveshapes extending substantially the whole length of the base layer 102Gfrom the EL21 side end portion to the EL22 side end portion. The firstconductor portion 621 is located in the vicinity of the EL11 side endportion of the base layer 102G, and overlaps with the first conductorportion 611 of the base layer 101G in planar view. The second conductorportion 622 is located in the vicinity of the EL12 side end portion ofthe base layer 102G, and overlaps with the second conductor portion 612of the base layer 101G in planar view.

The third conductor portion 623, the fourth conductor portion 624, andthe fifth conductor portion 625 each includes a line conductor extendingin the first direction. The widths (length in the second direction) ofthe fourth conductor portion 624 and the fifth conductor portion 625 arewider than the width of the third conductor portion 623.

The third conductor portion 623 is located in the vicinity of the EL22side end portion of the base layer 102G. The third conductor portion 623has a shape extending substantially the whole length of the base layer102G from the EL11 side end portion to the EL12 side end portion. TheEL11 side end portion of the third conductor portion 623 is connected tothe first conductor portion 621. The EL12 side end portion of the thirdconductor portion 623 is connected to the second conductor portion 622.

The fourth conductor portion 624 and the fifth conductor portion 625 arelocated in the vicinity of the EL21 side end portion of the base layer102G. The fourth conductor portion 624 has a shape extending from theEL11 side end portion of the base layer 102G to a middle location in thefirst direction. The EL11 side end portion of the fourth conductorportion 624 is connected to the EL21 side end portion of the firstconductor portion 621. The fifth conductor portion 625 has a shapeextending from the EL12 side end portion of the base layer 102G to amiddle location in the first direction. The EL12 side end portion of thefifth conductor portion 625 is connected to the EL21 side end portion ofthe second conductor portion 622. An end portion of the fourth conductorportion 624 opposite to the side connecting to the first conductorportion 621 and an end portion of the fifth conductor portion 625opposite to the side connecting to the second conductor portion 622 arenot connected and are separated from each other. The length of thefourth conductor portion 624 in the first direction is shorter than thelength of the fifth conductor portion 625 in the first direction.

The fourth conductor portion 624 of the conductor pattern 620 is shorterthan the fourth conductor portion 614 of the conductor pattern 610 inlength in the first direction. The fourth conductor portion 624 overlapsa predetermined-length portion of the fourth conductor portion 614 onthe EL11 side in planar view.

The fifth conductor portion 625 of the conductor pattern 620 is longerthan the fifth conductor portion 615 of the conductor pattern 610 inlength in the first direction. A predetermined-length portion of thefifth conductor portion 625 on the EL12 side overlaps the fifthconductor portion 615 in planar view.

An EL12 side region F61 of the fourth conductor portion 614 of theconductor pattern 610, which does not overlap the fourth conductorportion 624 in planar view, is arranged opposite to an EL11 side regionF62 of the fifth conductor portion 625 of the conductor pattern 620,which does not overlap the fifth conductor portion 615 in planar view,over the base layer 101G. These regions F61, F62 and the base layer 101Gconstitute a capacitor C10.

On the base layer 101G, interlayer-connector conductors 461, 462, 463,464, and 465 are provided. The interlayer-connector conductors 461, 462,463, 464, and 465 are formed preferably by filling through-holes thatpenetrates the base layer 101G with electrically conductive paste andsolidifying them. The electrically conductive paste includes anelectrically conductive material whose primary component is silver ortin.

The interlayer-connector conductor 461 connects the first conductorportion 611 of the conductor pattern 610 and the first conductor portion621 of the conductor pattern 620. A plurality of theinterlayer-connector conductors 461 is provided along the seconddirection. This interlayer-connector conductor causes to equatepotentials of the first conductor portions 611 and 621, and enables themto function as a single first conductor pattern.

The interlayer-connector conductor 462 connects the second conductorportion 612 of the conductor pattern 610 and the second conductorportion 622 of the conductor pattern 620. A plurality of theinterlayer-connector conductors 462 is provided along the seconddirection. This interlayer-connector conductor causes to equatepotentials of the second conductor portions 612 and 622, and enablesthem to function as a single second conductor pattern.

The interlayer-connector conductor 463 connects the third conductorportion 613 of the conductor pattern 610 and the third conductor portion623 of the conductor pattern 620. A plurality of theinterlayer-connector conductors 463 is provided along the firstdirection. This interlayer-connector conductor causes to equatepotentials of the third conductor portions 613 and 623, and enables themto function as a single third conductor pattern.

The interlayer-connector conductor 464 connects the fourth conductorportion 614 of the conductor pattern 610 and the fourth conductorportion 624 of the conductor pattern 620. A plurality of theinterlayer-connector conductors 464 is provided along the firstdirection. This interlayer-connector conductor causes to equatepotentials of the fourth conductor portions 614 and 624, and enablesthem to function as a single fourth conductor pattern.

The interlayer-connector conductor 465 connects the fifth conductorportion 615 of the conductor pattern 610 and the fifth conductor portion625 of the conductor pattern 620. A plurality of theinterlayer-connector conductors 465 is provided along the firstdirection. This interlayer-connector conductor causes to equatepotentials of the fifth conductor portions 615 and 625, and enables themto function as a single fifth conductor pattern.

Each foregoing conductor pattern defines and functions as an inductor inhigh frequency.

Connectors 501 and 502 that define and function as the externalconnection terminals are provided on the resist film 110G side of thebase body 100G. The connectors 501 and 502 each has a structure thatenables to establish electrical connection between an external circuitboard and the signal transmission cable 10G by physically connecting toa connector mount portion of an external circuit board, which is notillustrated in the drawing. The connectors 501 and 502 may be omitted.However, the use of the connectors 501 and 502 makes it possible toimprove reliability of connections between the signal transmission cable10G and first and second external circuit boards.

The connector 501 is disposed at the opening 111 in the resist film 110Gand connected to a middle point 611 ct of the first conductor portion611. The connector 502 is disposed at the opening 112 in the resist film110G and connected to a middle point 612 ct of the second conductorportion 612.

As described above, using the configuration of the present preferredembodiment makes it possible to provide the inductors and the capacitorusing the conductor patterns formed on the base layers 101G and 102G.Specifically, using the configuration of the present preferredembodiment makes it possible to realize a band-elimination filtercircuit whose equivalent circuit is depicted in FIG. 18. FIG. 18 is anequivalent circuit diagram of the signal transmission cable according tothe eighth preferred embodiment of the present invention.

In the signal transmission cable 10G of the present preferredembodiment, inductors L10, L201, L202, and a capacitor C10 are connectedbetween the connectors (external connection terminals) 501 and 502.Specifically, the inductor L201, the capacitor C10, and the inductorL202 are connected in series between the connectors 501 and 502.Further, the inductor L10 is connected in parallel to a series circuitof the inductor L201, the capacitor C10, and the inductor L202.

The inductor L10 includes the third conductor pattern, namely, the thirdconductor portions 613, 623, and the interlayer-connector conductor 463.More precisely, the inductor L10 also includes additional portions(portions 6111, 6211, 6121, and 6221 in FIG. 16 and FIG. 17) fromlocations where the first and second conductor patterns are connected tothe connectors 501 and 502 to a location where the third conductorpattern is connected and the interlayer-connector conductors 461 and 462connecting these portions. Each conductor pattern that constitutes thisinductor L10 corresponds to a first line conductor pattern.

The inductor L201 includes the fourth conductor pattern, namely, thefourth conductor portions 614, 624, and the interlayer-connectorconductor 464. More precisely, the inductor L201 further includesportions (portions 6112 and 6212 in FIG. 16 and FIG. 17) from a locationwhere the first conductor pattern is connected to the connector 501 to alocation where the fourth conductor pattern is connected and theinterlayer-connector conductor 461 connecting these portions.

The inductor L202 includes the fifth conductor pattern, namely, thefifth conductor portions 615, 625, and the interlayer-connectorconductor 465. More precisely, the inductor L202 further includesportions (portions 6122 and 6222 in FIG. 16 and FIG. 17) from a locationwhere the second conductor pattern is connected to the connector 502 toa location where the fifth conductor pattern is connected and theinterlayer-connector conductor 462 connecting these portions. Theconductor patterns that constitute these inductors L202 and L203 eachcorrespond to a second line conductor pattern.

The capacitor C10 includes, as described above, the region F61 of thefourth conductor portion 614, the region F62 of the fifth conductorportion 625, and the base layer 101G interposed between the regions F61and F62. As described above, the fourth conductor portions 614 and 624provided to define the regions F61 and F62 correspond to a firstportion, and the fifth conductor portions 615 and 625 correspond to asecond portion.

As described above, by using the configuration of the present preferredembodiment, an LC parallel resonance circuit is realized. Further, as isthe case with the seventh preferred embodiment, a band-eliminationfilter is provided and includes an attenuation pole frequency that isset at a first desired frequency f0 and that has a local maximum, atwhich the transmission loss is decreased, at a second desired frequencyf1 in its passband. Further, a signal transmission cable withband-elimination filter functionality is realized.

Further, in the configuration of the present preferred embodiment, theconductor pattern that constitutes the inductor includes two layers, andthese two layers are connected by the interlayer-connector conductor.Thus, the series resistance of the inductor is significantly reducedcompared with the case where the conductor pattern includes only onesingle layer. Further, the series resistance of the inductor issignificantly reduced without widening the width of the conductorpattern that constitutes the inductor. This improves the Q value of theinductor. Accordingly, a high-Q value LC parallel resonance circuit,namely, a band-elimination filter with steep attenuation characteristicis realized.

Further, in the configuration of the present preferred embodiment, theconductor pattern that constitutes the inductor includes two layers, andthe conductor pattern in these two layers are cut in the middle atlocations different from each other. The capacitor is formed preferablyby arranging conductor portions in the vicinities of cut sections toface each other. In this way, no additional capacitor conductor patternis needed, and the band-elimination filter of the LC parallel resonancecircuit is made smaller.

The number of the interlayer-connector conductors may be varied asneeded. For example, the interlayer-connector conductors 463 at themiddle positions of the third conductor portions 613 and 623 in thefirst direction may be omitted, or inversely the number of theinterlayer-connector conductor 463 may be increased. In a case where theinterlayer-connector conductors 463 at the middle position are omitted,bendability of the signal transmission cable 10G increases. However, atthe same time, magnetic field due to a current flowing through the thirdconductor portion 613 and magnetic field due to a current flowingthrough the third conductor portion 623 are prone to pass throughbetween the third conductor portions 613 and 623. This may slightlyreduce the Q value in some cases. On the other hand, in a case where thenumber of the interlayer-connector conductors 463 is increased, the Qvalue does not decrease. However, overall stiffness becomes higher, andthe bendability of the signal transmission cable 10G decreases.Accordingly, the interlayer-connector conductor may be arbitrarilyprovided in view of such conditions.

Further, in the foregoing configuration, the example is described inwhich the line widths of the fourth conductor portion and the fifthconductor portion that constitute the capacitors are made wider comparedto the line width of the first conductor portion in each layer.Alternatively, these conductor portions may have the same line width.Further, if need arises, it is possible to narrow the line widths of thefourth conductor portion and the fifth conductor portion that constitutethe capacitors compared to the line width of the first conductor portionin each layer.

Next, a signal transmission cable according to the ninth preferredembodiment of the present invention is described with reference to thedrawings. FIG. 19 is an exploded perspective view of the signaltransmission cable according to the ninth preferred embodiment of thepresent invention. A signal transmission cable 10H of the presentpreferred embodiment differs from the signal transmission cable 10Gdescribed in the eighth preferred embodiment in the number of the baselayers that constitute a base body 100H. Thus, only different sectionsare described in detail.

The base body 100H is formed preferably by stacking base layers 101H,102H, 103H, and 104H. The base layers 101H, 102H, 103H, and 104H arestacked in this order from a resist film 110H side.

The signal line conductor pattern 610 (hereinafter, simply referred toas “conductor pattern 610”) provided on the base layer 101H and thesignal line conductor pattern 630 (hereinafter, simply referred to as“conductor pattern 630”) provided on the base layer 103H are the sameshape as the signal line conductor pattern 610 described in the eighthpreferred embodiment.

The signal line conductor pattern 620 (hereinafter, simply referred toas “conductor pattern 620”) provided on the base layer 102H and thesignal line conductor pattern 640 (hereinafter, simply referred to as“conductor pattern 640”) provided on the base layer 104H are the sameshape as the signal line conductor pattern 620 described in the eighthpreferred embodiment.

A first conductor portion 611 of the conductor portion 610, a firstconductor portion 621 of the conductor pattern 620, a first conductorportion 631 of the conductor pattern 630, and a first conductor portion641 of the conductor pattern 640 are connected by a plurality ofinterlayer-connector conductors 461 penetrating through the base layers101H, 102H, and 103H.

A second conductor portion 612 of the conductor pattern 610, a secondconductor portion 622 of the conductor pattern 620, a second conductorportion 632 of the conductor pattern 630, and a second conductor portion642 of the conductor pattern 640 are connected by a plurality ofinterlayer-connector conductors 462 penetrating through the base layers101H, 102H, and 103H.

A third conductor portion 613 of the conductor pattern 610, a thirdconductor portion 623 of the conductor pattern 620, a third conductorportion 633 of the conductor pattern 630, and a third conductor portion643 of the conductor pattern 640 are connected by a plurality ofinterlayer-connector conductors 463 penetrating through the base layers101H, 102H, and 103H.

A fourth conductor portion 614 of the conductor pattern 610, a fourthconductor portion 624 of the conductor pattern 620, a fourth conductorportion 634 of the conductor pattern 630, and a fourth conductor portion644 of the conductor pattern 640 are connected by a plurality ofinterlayer-connector conductors 464 penetrating through the base layers101H, 102H, and 103H.

A fifth conductor portion 615 of the conductor pattern 610, a fifthconductor portion 625 of the conductor pattern 620, a fifth conductorportion 635 of the conductor pattern 630, and a fifth conductor portion645 of the conductor pattern 640 are connected by a plurality ofinterlayer-connector conductors 465 penetrating through the base layers101H, 102H, and 103H.

A region F61 of the fourth conductor portion 614 of the conductorpattern 610 and a region F62 of the fifth conductor portion 625 of theconductor pattern 620 are arranged opposite to each other over the baselayer 101H. This defines a capacitor C11.

The region F62 of the fifth conductor portion 625 of the conductorpattern 620 and a region F63 of the fourth conductor portion 634 of theconductor pattern 630 are arranged opposite to each other over the baselayer 102H. This defines a capacitor C12.

The region F63 of the fourth conductor portion 634 of the conductorpattern 630 and a region F64 of the fifth conductor portion 645 of theconductor pattern 640 are arranged opposite to each other over the baselayer 103H. This defines a capacitor C13.

According to such a configuration, a plurality of the capacitors C11,C12, and C13 are provided, and a range of achievable capacitance issignificantly widened.

Further, in the present preferred embodiment, the example is describedin which the capacitors are provided in respective base layers.Alternatively, the capacitor may not be provided in some base layers.For example, the conductor pattern 620 and the conductor pattern 630 mayhave the same shape, and the conductor pattern 610 and the conductorpattern 640 may have the same shape. Further, the areas opposing overthe base layer may be made different for each base layer. This makes itpossible to further widen the range of achievable capacitance.

In the present preferred embodiment, pairs of the same shape conductorpatterns are preferably provided. Alternatively, in such aconfiguration, one of the pairs of the conductor patterns may bereplaced with a single conductor pattern, and this single conductorpattern may be sandwiched between two conductor patterns having the sameshape. Further, by applying this alternative configuration, an oddnumber of the conductor patterns may be used.

Further, using the configuration of the present preferred embodimentmakes it possible to provide each inductor with four layers of conductorpatterns. This further reduces the series resistance of each inductor,and the Q value is further improved.

Next, a signal transmission cable according to the tenth preferredembodiment of the present invention is described with reference to thedrawings. FIG. 20 is an exploded perspective view of the signaltransmission cable according to the tenth preferred embodiment of thepresent invention. FIG. 21 is plan views of conductor patterns inrespective base layers of the signal transmission cable according to thetenth preferred embodiment of the present invention.

As depicted in FIG. 20 and FIG. 21, a signal transmission cable 10Iincludes a flat base body 100I extending in two directions, the firstdirection and the second direction. The thickness of the base body 100Imay be arbitrarily determined, and preferably is about 0.5 mm, forexample. An insulating resist film 110I is provided on one of flatsurfaces (surfaces parallel to the first direction and the seconddirection) of the base body 100I so as to cover substantially the entirearea thereof.

The base body 100I is formed preferably by stacking base layers 101I,102I, 103I, and 104I. The base layers 101I, 102I, 103I, and 104I eachincludes a flexible insulating flat film such as, for example, a liquidcrystal polymer. The base layers 101I, 102I, 103I, and 104I are stackedin this order from the resist film 110I side. In other words, theinsulating resist film 110I is provided on a flat surface of the baselayer 101I opposite to the base layer 102I.

Signal line conductor patterns 711 and 712 (hereinafter, simply referredto as “conductor patterns 711 and 712”) are provided on a resist film110I side surface of the base layer 101I. The conductor patterns 711 and712 are composed of a metal having high electrical conductivity and thelike, such as a copper foil and the like. The conductor pattern 711includes a first line portion 7111, a second line portion 7112, a thirdline portion 7113, and a fourth line portion 7114.

The first line portion 7111 and the third line portion 7113 have shapesextending in the first direction, and the second line portion 7112 andthe fourth line portion 7114 have shapes extending in the seconddirection. The first line portion 7111 is located in the vicinity of anEL22 end portion of the base layer 101I, connected to aninterlayer-connector conductor 471, which will be described below, atone end portion, and connected to one end portion of the second lineportion 7112 at the other end portion. The second line portion 7112 islocated in a region of the base layer 101I on an EL11 end portion side,connected to the first line portion 7111 at one end portion, andconnected to one end portion of the third line portion 7113 at the otherend portion. The third line portion 7113 is located in the vicinity ofan EL21 end portion of the base layer 101I, connected to the second lineportion 7112 at one end portion, and connected to one end portion of thefourth line portion 7114 at the other end portion. The fourth lineportion 7114 is located in the vicinity of an EL12 end portion of thebase layer 101I, and connected to the third line portion 7113 at one endportion.

According to such a configuration, the conductor pattern 711 has aloop-shaped portion of which is cut off in planar view, namely, a C-loopshape.

The conductor pattern 712 has a shape extending the whole length fromthe EL21 end portion to the EL22 end portion in the second direction,and is located between the EL11 end portion of the base layer 101I andthe conductor pattern 711 while being separated from the conductorpattern 711.

Signal line conductor patterns 721 and 722 (hereinafter, simply referredto as “conductor patterns 721 and 722”) are located on a base layer 101Iside surface of the base layer 102I. The conductor patterns 721 and 722are composed of a metal having high electrical conductivity and thelike, such as a copper foil and the like. The conductor pattern 721includes a first line portion 7211, a second line portion 7212, and athird line portion 7213.

The first line portion 7211 and the third line portion 7213 have shapesextending in the first direction, and the second line portion 7212 has ashape extending in the second direction. The first line portion 7211 islocated in the vicinity of an EL22 end portion of the base layer 102I,connected to the interlayer-connector conductor 471, which will bedescribed below, at one end portion, and connected to one end portion ofthe second line portion 7212 at the other end portion. The second lineportion 7212 is provided in a region of the base layer 102I on an EL12end portion side, connected to the first line portion 7211 at one endportion, and connected to one end portion of the third line portion 7213at the other end portion. The third line portion 7213 is located in thevicinity of an EL21 end portion of the base layer 102I, and connected tothe second line portion 7212 at one end portion. The third line portion7213 has a shape extending the whole length from an EL11 side endportion to an EL12 side end portion.

According to such a configuration, the conductor pattern 721 includes aloop-shaped portion of which is cut off in planar view, namely, a C-loopshape.

The conductor pattern 722 has a shape extending in the second directionbetween the EL21 end portion and the third line portion 7213 of theconductor pattern 721, and is separated from the conductor pattern 721.The conductor pattern 722 and a region F71 of the conductor pattern 712are arranged opposite to each other over the base layer 101I. Thisdefines a capacitor C21.

Signal line conductor patterns 731 and 732 (hereinafter, simply referredto as “conductor patterns 731 and 732”) are provided on a base layer102I side surface of the base layer 103I. The conductor patterns 731 and732 are composed of a metal having high electrical conductivity and thelike, such as a copper foil and the like. The conductor pattern 731includes a first line portion 7311, a second line portion 7312, a thirdline portion 7313, and a fourth line portion 7314.

The first line portion 7311 and the third line portion 7313 have shapesextending in the first direction, and the second line portion 7312 andthe fourth line portion 7314 have shapes extending in the seconddirection. The first line portion 7311 is located in the vicinity of anEL21 end portion of the base layer 103I, connected to theinterlayer-connector conductor 472, which will be described below, atone end portion, and connected to one end portion of the second lineportion 7312 at the other end portion. The second line portion 7312 islocated in a region of the base layer 103I on an EL11 end portion side,connected to the first line portion 7311 at one end portion, andconnected to one end portion of the third line portion 7313 at the otherend portion. The third line portion 7313 is located in the vicinity ofan EL22 end portion of the base layer 103I, connected to the second lineportion 7312 at one end portion, and connected to the fourth lineportion 7314 at the other end portion. The fourth line portion 7314 islocated in the vicinity of an EL12 end portion of the base layer 103I,connected to the third line portion 7313 at one end portion, and has ashape extending the whole length from the EL21 end portion to the EL22end portion.

The conductor pattern 732 has a shape extending in the second directionfrom the EL21 end portion for a predetermined length, which does notreach the EL22 end portion. Specifically, the conductor pattern 732 hasa shape extending in the second direction except a region where aninterlayer-connector conductor 474, which will be described below, canbe provided. The conductor pattern 732 is separated from the conductorpattern 731. A region F73 of the conductor pattern 732 and a region F72of the conductor pattern 722 are arranged opposite to each other overthe base layer 102I. This defines a capacitor C22.

Signal line conductor patterns 741 and 742 (hereinafter, simply referredto as “conductor patterns 741 and 742”) are provided on a base layer103I side surface of the base layer 104I. The conductor patterns 741 and742 are composed of a metal having high electrical conductivity and thelike, such as a copper foil and the like. The conductor pattern 741includes a first line portion 7411, a second line portion 7412, a thirdline portion 7413, and a fourth line portion 7414.

The first line portion 7411 and the third line portion 7413 have shapesextending in the second direction, and the second line portion 7412 andthe fourth line portion 7414 have shapes extending in the firstdirection. The first line portion 7411 is located in the vicinity of anEL11 end portion of the base layer 104I, and has a shape extending thewhole length from an EL21 end portion to an EL22 end portion. The secondline portion 7412 is located in a region of the base layer 104I on theEL22 end portion side, connected to the first line portion 7411 at oneend portion, and connected to one end portion of the third line portion7413 at the other end portion. The second line portion 7412 has a shapeextending the whole length from an EL11 side end portion to an EL12 sideend portion. The third line portion 7413 is located in the vicinity ofthe EL12 end portion of the base layer 104I, connected to the secondline portion 7412 at one end portion, and connected to one end portionof the fourth line portion 7414 at the other end portion. The third lineportion 7413 has a shape extending the whole length from the EL11 sideend portion to the EL12 side end portion. The fourth line portion 7414is located in the vicinity of the EL21 end portion of the base layer104I, connected to the third line portion 7413 at one end portion, andconnected to an interlayer-connector conductor 472, which will bedescribed below, at the other end portion.

According to such a configuration, the conductor pattern 741 has aloop-shaped portion of which is cut off in planar view, namely, a C-loopshape.

A region F74 of the first line portion 7411 and the conductor pattern732 are arranged opposite to each other over the base layer 103I. Thisdefines a capacitor C23.

The interlayer-connector conductor 471 connects the conductor patterns711 and 721, each having the C-loop shape, in a stacking direction. Theconductor patterns 711 and 721 connected by the interlayer-connectorconductor 471 define a spiral conductor pattern whose axial direction isaligned to the stacking direction of the base layers. This spiralconductor pattern defines an inductor L11.

The interlayer-connector conductor 472 connects the conductor patterns731 and 741, each having the C-loop shape, in the stacking direction.The conductor patterns 731 and 741 connected by the interlayer-connectorconductor 472 define a spiral conductor pattern whose axial direction isaligned to the stacking direction of the base layers. This spiralconductor pattern defines an inductor L21.

An interlayer-connector conductor 473 connects the conductor pattern712, the conductor pattern 721, and the conductor pattern 732 in thestacking direction. The interlayer-connector conductor 474 connects theconductor pattern 722 and the conductor pattern 741 in the stackingdirection. An interlayer-connector conductor 475 connects the conductorpattern 711 and the conductor pattern 731 in the stacking direction.

Connectors 501 and 502 that define and function as external connectionterminals are provided on the resist film 110I side of the base body100I. The connectors 501 and 502 each has a structure that enables toestablish electrical connection between an external circuit board andthe signal transmission cable 10I by physically connecting to aconnector mount portion of an external circuit board, which is notillustrated in the drawings. The connectors 501 and 502 may be omitted.However, the use of the connectors 501 and 502 enables to improvereliability of connections between the signal transmission cable 10I andfirst and second external circuit boards.

The connector 501 is disposed at the opening 111 in the resist film 110Iand connected to the conductor pattern 712. The connector 502 isdisposed at the opening 112 in the resist film 110I and connected to theconductor pattern 711.

As described above, using the configuration of the present preferredembodiment makes it possible to provide the inductors and the capacitorswith the conductor patterns on the base layers 101I, 102I, 103I, and104I. Specifically, using the configuration of the present preferredembodiment makes it possible to realize a band-elimination filtercircuit whose equivalent circuit is depicted in FIG. 22. FIG. 22 is anequivalent circuit diagram of the signal transmission cable according tothe tenth preferred embodiment of the present invention.

In the signal transmission cable 10I of the present preferredembodiment, the inductors L11 and L21 and the capacitors C21, C22, andC23 are connected between the connectors (external connection terminals)501 and 502. Specifically, the inductor L11 and the inductor L21 areconnected in parallel between the connectors 501 and 502. The capacitorsC21, C22, and C23 are connected in parallel to each other, and thiscapacitor parallel circuit is connected between the connector 501 andthe inductor L21.

The inductor L11 is realized with the spiral conductor pattern includingthe conductor patterns 711, 721, and the interlayer-connector conductor471. In the inductor L11, the conductor pattern 721 is connected to theconnector 501 via the conductor pattern 712 and the interlayer-connectorconductor 473, and the conductor pattern 711 is directly connected tothe connector 502.

The inductor L21 is realized with the spiral conductor pattern includingthe conductor patterns 731, 741, and the interlayer-connector conductor472. In the inductor L21, the conductor pattern 741 is connected to theconnector 501 via the capacitors C21, C22, and C23, and the conductorpattern 731 is connected to the connector 502 via theinterlayer-connector conductor 475 and the fourth line portion 7114 ofthe conductor pattern 711.

As described above, by using the configuration of the present preferredembodiment, an LC parallel resonance circuit is realized. Further, as isthe cases with the seventh, eighth, and ninth preferred embodiments, aband-elimination filter is provided with an attenuation pole frequencythat is set at the first desired frequency f0 and that has a localmaximum, at which the transmission loss is reduced, at the seconddesired frequency f1 in its passband. Further, a signal transmissioncable with band-elimination filter functionality is realized.

Further, using the configuration of the present preferred embodimentmakes it possible to realize each inductor with the spiral conductorpattern. Thus, an inductor having a higher Q value compared withinductors having different shapes is realized. Further, in theconfiguration of the present preferred embodiment, the Q value ofinductor is further improved since the spiral inductor is has a largestpossible dimension or radius of air core portion within the dimension ofthe base body 100I.

Further, by using the configuration of the present preferred embodiment,in a transmission path from the connector 501 defining and functioningas a starting point to the connector 502 defining and functioning as anending point, the inductor L11 and the inductor L21 are arranged so asto wind in opposite directions when the base body 100I is viewed inplanar view. Further, the conductor patterns 711 and 721 constitutingthe inductor L11 overlap the conductor patterns 731 and 741 constitutingthe inductor L21 in planar view. This causes a mutual inductance whosecoupling coefficient K is negative (K<0) between the inductors L11 andL21. Adjusting this coupling coefficient makes it possible to adjustattenuation characteristics.

Next, a signal transmission cable according to the eleventh preferredembodiment of the present invention is described with reference to thedrawings. FIG. 23 is an exploded perspective view of the signaltransmission cable according to the eleventh preferred embodiment of thepresent invention.

A signal transmission cable 10J of the present preferred embodiment ispreferably configured such that an additional line portion 7415 is addedto the conductor pattern 741 of the signal transmission cable 10Idescribed in the tenth preferred embodiment to form a conductor pattern7410. Thus, only portions different from the signal transmission cable10I according to the tenth preferred embodiment are described in detail.

The conductor pattern 7410 includes the first line portion 7411, thesecond line portion 7412, the third line portion 7413, and the fourthline portion 7414, which are the same elements as in the conductorpattern 741, in addition to the additional line portion 7415. Theadditional line portion 7415 is located in the vicinity of the EL21 endportion of the base layer 104J, and has a shape extending in the firstdirection. The additional line portion 7415 is connected to the EL21side end portion of the first line portion 7411. The additional lineportion 7415 and the first line portion 7311 of the conductor pattern731 are arranged opposite to each other over the base layer 103J.

Such a configuration further defines a capacitor C24 connected inparallel to the inductor L21. Such capacitor C24 makes it possible toadjust attenuation characteristics and facilitates achievement ofdesired attenuation characteristics.

Next, a signal transmission cable according to the twelfth preferredembodiment of the present invention is described with reference to thedrawings. FIG. 24 is plan views of conductor patterns in respective baselayers of the signal transmission cable according to the twelfthpreferred embodiment of the present invention.

A signal transmission cable 10K of the present preferred embodimentdiffers from the signal transmission cable 10I described in the tenthpreferred embodiment in winding directions of conductor patterns 731′and 741′ that constitute the inductor L21. In other words, in thetransmission path from the connector 501 defining and functioning as astarting point to the connector 502 defining and functioning as anending point, the inductor L11 and the inductor L21 are arranged so asto wind in the same direction when the base body 100I is viewed inplanar view. This results in a mutual inductance whose couplingcoefficient K is positive (K>0) between the inductors L11 and L21.Adjusting this coupling coefficient makes it possible to adjustattenuation characteristics.

FIG. 25 is a graph depicting bandpass characteristics of the signaltransmission cables according to the tenth and twelfth preferredembodiments of the present invention. As depicted in FIG. 25, a steepattenuation characteristic is obtained in a case where the inductors L11and L21 are coupled so as to have a negative coupling coefficient (K<0).Further, as depicted in FIG. 25, in a case where the inductors L11 andL21 are coupled so as to have a positive coupling coefficient (K<0),attenuation characteristics that cannot be achieved with any negativecoupling coefficient (K<0) can be achieved. For example, as depicted inFIG. 25, a local maximum of passband is able to be adjusted at afrequency f2A that is different from a frequency f1A of a local maximumof the passband in the configuration with the negative couplingcoefficient (K<0). Further, a wider-width attenuation band is obtainedon the higher frequency side of the attenuation pole frequency whencoupled with a negative coupling coefficient (K<0), and a narrower-widthattenuation band is obtained on the higher frequency side of theattenuation pole frequency when coupled with a positive couplingcoefficient (K>0). In this way, adjusting the coupling coefficientenables to arbitrarily set up the attenuation characteristics or thebandpass characteristics.

Next, a signal transmission cable according to the thirteenth preferredembodiment of the present invention is described with reference to thedrawings. FIG. 26 is an exploded perspective view of the signaltransmission cable according to the thirteenth preferred embodiment ofthe present invention.

In the signal transmission cables according to the eighth to eleventhpreferred embodiments, the connectors 501 and 502 are directly connectedto the conductor patterns constituting a band-elimination filter.However, a signal transmission cable 10L of the present preferredembodiment includes routing conductors in addition to the conductorpatterns constituting a band-elimination filter, and these routingconductors are connected to the connectors 501 and 502. The presentpreferred embodiment is preferably provided by adding routing conductors616 and 626 to the signal transmission cable 10G according to the eighthpreferred embodiment. Alternatively, the routing conductors 616 and 626described in the present preferred embodiment may also be applied to theother signal transmission cables according to the eighth to eleventhpreferred embodiments.

The routing conductors 616 are provided on a resist film 110L sidesurface of a base layer 101L. The routing conductors 616 are arranged onboth ends of a conductor pattern 610L in the first direction. Therouting conductors 616 are each connected to the conductor pattern 610Land each have a shape extending in the first direction. End portions ofthe routing conductors 616 opposite to end portions connected to theconductor pattern 610L are respectively connected to the connectors 501and 502.

The routing conductors 626 are provided on a base layer 101L sidesurface of a base layer 102L. The routing conductors 626 are arranged onboth ends of a conductor pattern 620L in the first direction. Therouting conductors 626 are each connected to the conductor pattern 620Land each have a shape extending in the first direction. The routingconductors 626 have shapes that overlap the routing conductors 616 inplanar view. The routing conductors 626 are connected, byinterlayer-connector conductors 466, to the routing conductors 616 thatoverlap in planar view.

Such a configuration makes it possible to provide the signaltransmission cable 10L in an appropriate shape in response to a distancebetween first and second external circuit boards, which are to beconnected to the connectors 501 and 502, without changing thefunctionality of band-elimination filter.

In the present preferred embodiment, an example is described in whichthe width of the base body 100L (length in the second direction) isconstant between the connectors 501 and 502, namely, for the wholelength in the first direction. Alternatively, only the widths of routingconductors 616 and 626 portions may be made narrower.

Alternatively, the routing conductors 626 may be omitted, and theconfiguration may be provided only with the routing conductors 616. Withthis configuration, flexibility at portions of the base body where therouting conductors are located can be provided. On the other hand, in acase where the routing conductors 616 and 626 are used, the totaldirect-current resistance of the routing conductors as a whole isreduced, and the transmission loss is further suppressed or prevented.

The signal transmission cable having the foregoing configuration isapplicable to a communication device module, which will be describedbelow. FIG. 27 is a block diagram of a communication device moduleaccording to a preferred embodiment of the present invention. FIG. 28 isa side view depicting a schematic configuration of a communicationdevice module according to a preferred embodiment of the presentinvention. FIG. 27 and FIG. 28 depict a preferred embodiment in whichthe signal transmission cable 10B described in the third preferredembodiment is used.

As depicted in FIG. 27, a communication device module 900 of the presentpreferred embodiment preferably includes an antenna 901, a WiFitransceiver 911, a cellular transceiver 912, a GPS receiver 913, aband-elimination filter (BEF) 921, and a bandpass filter (BPF) 922.

The antenna 901 is connected to the WiFi transceiver 911 and thecellular transceiver 912 via the band-elimination filter 921. Further,the antenna 901 is connected to the GPS receiver 913 via the bandpassfilter 922.

The WiFi transceiver 911 transmits and receives WiFi communicationsignals that use a frequency band at, for example, a 2.4 GHz band andthe like. The cellular transceiver 912 transmits and receives cellularcommunication signals that use a frequency band at, for example, a 900MHz band and the like or a 1.9 GHz band and the like. The GPS receiver913 receives GPS signals near at 1.5 GHz.

The band-elimination filter 921 attenuates the frequency band of the GPSsignals and passes the frequency bands of the WiFi communication signalsand the cellular communication signals. The bandpass filter 922 passesthe frequency band of the GPS signals and attenuates the frequency bandsother than the frequency band of the GPS signals.

The signal transmission cable 10B described in the third preferredembodiment is used in this band-elimination filter 921. By using thissignal transmission cable 10B, a band-elimination filter having steepattenuation characteristics and a narrow attenuation band is realized.Accordingly, in a case where the attenuation pole is set at thefrequency band of the GPS signals, the GPS signals are attenuated, andother communication signals (for example, 1.9 GHz band for the cellularcommunication signals) and the like, which are close to the frequencyband of the GPS signals, are able to be transmitted without attenuation.

The communication device module 900 having such a circuit configurationincludes a front end board 990, an antenna board 991, and the signaltransmission cable 10B. On a mount surface of the front end board 990,circuit components that realize the WiFi transceiver 911, the cellulartransceiver 912, the GPS receiver 913, and the like are mounted. Theantenna 901 is provided on the antenna board 991. The antenna board 991is arranged on the mount surface side of the front end board 990 in sucha manner to be separated from the front end board 990.

As depicted in FIG. 28, the connector 501 of the signal transmissioncable 10B is connected to a front end board 990 side surface of theantenna board 991. The connector 502 of the signal transmission cable10B is connected to an antenna board 991 side surface (mount surface) ofthe front end board 990. Since the signal transmission cable 10B isflexible, a bent portion is able to be provided in the middle in theextending direction. As described above, providing the bent portionenables the signal transmission cable 10B to connect the front end board990 and the antenna board 991 while being in a state where the signaltransmission cable 10B is arranged so as not to touch the circuitcomponent.

Further, as described above, providing the band-elimination filter inthe signal transmission cable 10B eliminates the need to provide theband-elimination filter on the front end board 990 or the antenna board991. Accordingly, the front end board 990 or the antenna board 991 ismuch smaller. Further, providing the band-elimination filter in thesignal transmission cable 10B improves filter characteristics(attenuation characteristics and bandpass characteristics) of theband-elimination filter. Accordingly, communication characteristics ofthe communication device module 900 are significantly improved.

Next, a signal transmission cable according to the fourteenth preferredembodiment of the present invention is described with reference to thedrawings. FIG. 29 is an exploded perspective view of the signaltransmission cable according to the fourteenth preferred embodiment ofthe present invention. In FIG. 29, a protective layer and connecters areomitted from the illustration.

A diplexer-type signal transmission cable 90 of the present preferredembodiment includes a base body 100M that is formed preferably bystacking base layers 101M, 102M, 103M, and 104M.

The base layer 101M includes partial regions 101M1, 101M2, and 101M3.The partial regions 101M1 and 101M2 have elongated shapes extending in alengthwise direction and are arranged side by side along the widthdirection with a gap in between. The partial region 101M3 is arranged atend portions of the partial regions 101M1 and 101M2 in the lengthwisedirection and connects the partial regions 101M1 and 101M2. According tothis configuration, the base layer 101M has a shape that is separatedinto two regions in the width direction in the middle in the lengthwisedirection.

The base layer 102M includes partial regions 102M1, 102M2, and 102M3.The partial regions 102M1 and 102M2 have elongated shapes extending in alengthwise direction and are arranged side by side along the widthdirection with a gap in between. The partial region 102M3 is arranged atend portions of the partial regions 102M1 and 102M2 in the lengthwisedirection and connects the partial regions 102M1 and 102M2. The baselayer 102M has a shape that is separated into two regions in the widthdirection in the middle in the lengthwise direction.

The base layer 103M includes partial regions 103M1, 103M2, and 103M3.The partial regions 103M1 and 103M2 have elongated shapes extending in alengthwise direction and are arranged side by side along the widthdirection with a gap in between. The partial region 103M3 is disposed atends of the partial regions 103M1 and 103M2 in the lengthwise directionand connects the partial regions 103M1 and 103M2. The base layer 103Mhas a shape that is separated into two regions in the width direction inthe middle in the lengthwise direction.

The base layer 104M includes partial regions 104M1, 104M2, and 104M3.The partial regions 104M1 and 104M2 have elongated shapes extending in alengthwise direction and are arranged side by side along the widthdirection with a gap in between. The partial region 104M3 is disposed atend portions of the partial regions 104M1 and 104M2 in the lengthwisedirection and connects the partial regions 104M1 and 104M2. The baselayer 104M has a shape that is separated into two regions in the widthdirection in the middle in the lengthwise direction.

In a second base portion composed of the partial regions 101M2, 102M2,103M2, and 104M2 in the base body 100M, the same conductor patterns asones described in the ninth preferred embodiment are provided.Accordingly, a band-elimination filter is realized with the second baseportion including the partial regions 101M2, 102M2, 103M2, and 104M2 inthe base body 100M.

On a principal surface (one of principal surfaces of the base body 100M)of the base layer 101M in the partial region 101M1 opposite to the baselayer 102M side, conductor patterns 801M1 and 803M1 are provided. Theconductor pattern 801M1 includes a first portion conductor pattern801M11 and a second portion conductor pattern 801M12.

The first portion conductor pattern 801M11 and the conductor pattern803M1 are arranged along the lengthwise direction of the partial region101M1 with a gap in between. The first portion conductor pattern 801M11and the conductor pattern 803M1 have the same or substantially the samewidth, and this width is wider than the width of the second portionconductor pattern 801M12. In term of the functionality, they areprovided with widths needed to form the following capacitor.

The second portion conductor pattern 801M12 is arranged adjacent to thefirst portion conductor pattern 801M11 in the width direction of thepartial region 101M1. The second portion conductor pattern 801M12 is aloop-shaped conductor pattern. The loop-shaped conductor pattern has aloop shape, part of which is cut.

A side end portion of the first portion conductor pattern 801M11 on oneend portion of the partial region 101M1 is connected to one end portion(outer circumferential side end portion) of the second portion conductorpattern 801M12 near the one end portion of the partial region 101M1.These first portion conductor pattern 801M11 and the second portionconductor pattern 801M12 are connected to a routing conductor pattern841M formed near the one end portion of the partial region 101M1.

A side end portion of the conductor pattern 803M1 on the other endportion of the partial region 101M1 is connected to a routing conductorpattern 842M located near the other end portion of the partial region101M1.

On a base layer 101M side principal surface of the base layer 102M inthe partial region 102M1, a conductor pattern 801M2 and a capacitivecoupling conductor pattern 810M1 are provided. The conductor pattern801M2 includes a first portion conductor pattern 801M21 and a secondportion conductor pattern 801M22.

The first portion conductor pattern 801M21 preferably is rectangular orsubstantially rectangular and arranged opposite to a portion of thefirst portion conductor pattern 801M11 over the base layer 101M. Thefirst portion conductor pattern 801M21 is connected to the first portionconductor pattern 801M11 via a connection conductor 860 that passesthrough the base layer 101M in the thickness direction.

The second portion conductor pattern 801M22 is arranged adjacent to thefirst portion conductor pattern 801M21 in the width direction of thepartial region 102M1. The second portion conductor pattern 801M22 is aloop-shaped conductor pattern. The second portion conductor pattern801M22 overlaps the second portion conductor pattern 801M12 when viewedin a direction orthogonal to the principal surface. One end portion(outer circumferential side end portion) of the second portion conductorpattern 801M22 is connected to the first portion conductor pattern801M21. The other end portion (inner circumferential side end portion)of the second portion conductor pattern 801M22 is connected to the otherend portion (inner circumferential side end portion) of the secondportion conductor pattern 801M12 via the connection conductor 860 thatpasses through the base layer 101M in the thickness direction.

The capacitive coupling conductor pattern 810M1 preferably isrectangular or substantially rectangular or substantially rectangularand arranged opposite to both the first portion conductor pattern 801M11and the conductor pattern 803M1 over the base layer 101M. Opposingportions of the capacitive coupling conductor pattern 810M1 and thefirst portion conductor pattern 801M11 form a capacitor Ct21. Opposingportions of the capacitive coupling conductor pattern 810M1 and theconductor pattern 803M1 define a capacitor Ct10.

On a base layer 102M side principal surface of the base layer 103M inthe partial region 103M1, a capacitive coupling conductor pattern 810M2and a conductor pattern 802M1 are provided. The conductor pattern 802M1includes a first portion conductor pattern 802M11 and a second portionconductor pattern 802M12.

The capacitive coupling conductor pattern 810M2 and the first portionconductor pattern 802M11 are arranged along the lengthwise direction ofthe partial region 103M1 with a gap in between. The capacitive couplingconductor pattern 810M2 and the first portion conductor pattern 802M11have the same or substantially the same width. The capacitive couplingconductor pattern 810M2 is connected to the first portion conductorpattern 801M21 via the connection conductor 860 that passes through thebase layer 102M in the thickness direction.

The first portion conductor pattern 802M11 preferably is rectangular orsubstantially rectangular or substantially rectangular and arrangedopposite to a portion of the capacitive coupling conductor pattern 810M1over the base layer 102M. The first portion conductor pattern 802M11 isconnected to the capacitive coupling conductor pattern 810M1 via theconnection conductor 860 that passes through the base layer 102M in thethickness direction.

The second portion conductor pattern 802M12 is arranged adjacent to thecapacitive coupling conductor pattern 810M2 in the width direction ofthe partial region 103M1. The second portion conductor pattern 802M12 isa loop-shaped conductor pattern. One end portion (outer circumferentialside end portion) of the second portion conductor pattern 802M12 isconnected to the first portion conductor pattern 802M11. The other endportion (inner circumferential side end portion) of the second portionconductor pattern 802M12 overlaps the other end portion (innercircumferential side end portion) of the second portion conductorpattern 801M12 when viewed in the direction orthogonal to the principalsurface. The other end portion (inner circumferential side end portion)of the second portion conductor pattern 802M12 is connected to the otherend portion (inner circumferential side end portion) of the secondportion conductor pattern 801M22 via the connection conductor 860 thatpasses through the base layer 102M in the thickness direction.

The capacitive coupling conductor pattern 810M2 preferably isrectangular or substantially rectangular and arranged opposite to boththe first portion conductor pattern 801M21 and the capacitive couplingconductor pattern 810M1 over the base layer 102M. The capacitivecoupling conductor pattern 810M2 is connected to the first portionconductor pattern 801M21 via the connection conductor 860 that passesthrough the base layer 102M in the thickness direction. Opposingportions of the capacitive coupling conductor pattern 810M1 and 810M2define a capacitor Ct22.

On a base layer 103M side principal surface of the base layer 104M inthe partial region 104M1, a conductor pattern 802M2 is provided. Theconductor pattern 802M2 includes a first portion conductor pattern802M21 and a second portion conductor pattern 802M22.

The first portion conductor pattern 802M21 preferably is rectangular orsubstantially rectangular and arranged opposite to a portion of thecapacitive coupling conductor pattern 810M2 and the first portionconductor pattern 802M11 over the base layer 103M. The first portionconductor pattern 802M21 is connected to the first portion conductorpattern 802M11 via the connection conductor 860 that passes through thebase layer 103M in the thickness direction. Opposing portions of thefirst portion conductor pattern 802M21 and the capacitive couplingconductor pattern 810M2 define a capacitor Ct23.

The second portion conductor pattern 802M22 is a loop-shaped conductorpattern. The second portion conductor pattern 802M22 overlaps the secondportion conductor pattern 802M12 when viewed in the direction orthogonalto the principal surface. One end portion (outer circumferential sideend portion) of the second portion conductor pattern 802M22 is connectedto the first portion conductor pattern 802M21. The other end portion(inner circumferential side end portion) of the second portion conductorpattern 802M22 is connected to the other end portion (innercircumferential side end portion) of the second portion conductorpattern 802M12 via the connection conductor 860 that passes through thebase layer 103M in the thickness direction.

A spiral-shaped inductor Lt10 having an axial direction along thethickness direction of the base body 100M is formed preferably byarranging the second portion conductor patterns 801M12, 801M22, 802M12,and 802M22 and connecting the inner circumferential side end portions ofthese conductor patterns with the connection conductor 860 as describedabove.

Having such a configuration enables to realize a circuit configurationin which a series circuit of the inductor Lt10 and the capacitor Ct10 isconnected and the capacitors Ct21, Ct22, and Ct23 are connected inparallel to the inductor Lt10. In other words, a bandpass filter circuithaving both LC series resonance and LC parallel resonance is able to beconfigured.

Further, a diplexer-type signal transmission cable is provided toinclude a bandpass filter and a band-elimination filter are connected toa common terminal that is realized with the routing conductors 841M.

FIG. 30 is a graph depicting transmission characteristics of adiplexer-type signal transmission cable according to the fourteenthpreferred embodiment of the present invention. A solid line in FIG. 30represents a bandpass characteristic of a transmission path thattransmits from the common terminal to a first individual terminal viathe band-elimination filter. A dashed line in FIG. 30 represents abandpass characteristic of a transmission path that transmits from thecommon terminal to a second individual terminal via the bandpass filter.

As depicted in FIG. 30, between the common terminal and the secondindividual terminal, a high-frequency signal desired to transmit atfrequency f0 is able to be transmitted with low loss, and ahigh-frequency signal desired to attenuate at frequency f1 is greatlyattenuated. Further, between the common terminal and the firstindividual terminal, a high-frequency signal desired to cut off at thefrequency f0 is greatly attenuated, and a high-frequency signal desiredto pass at the frequency f1 can be transmitted with low loss.

Here, as depicted in FIG. 30, even in a case where the frequencies f0and f1 are close to each other, desired transmission characteristicsbetween the terminals is achieved. Specifically, the frequency f0 is aGPS signal frequency at approximately 1.575 GHz, and the frequency f1 isa 1.7 GHz communication band. The GPS signals are transmitted from thecommon terminal to the second individual terminal. The communicationsignals are transmitted between the common terminal and the firstindividual terminal.

In this way, even in a case where the frequency difference isapproximately 200 MHz, the GPS signals are transmitted to the secondindividual terminal with low loss, and transmission of the communicationsignals to the second individual terminal is greatly reduced. On theother hand, the communication signals are transmitted to the firstindividual terminal with low loss, and transmission of the GPS signalsto the first individual terminal is greatly reduced. In other words,sufficient isolation is secured between the first individual terminaland the second individual terminal in a desired frequency band.

Further, a high-frequency diplexer is realized with the base body 100M,in which the respective conductor patterns are formed preferably bymatching the passband of the bandpass filter with the stop band(attenuation band) of the band-elimination filter. This makes itpossible to realize a thin high-frequency diplexer having excellenttransmission characteristics.

The flat cable type high-frequency diplexer 90 of the present preferredembodiment can be used, for example, for a component including theband-elimination filter (BEF) 921, the bandpass filter (BPF) 922, andthe transmission line portion connecting these to the antenna 901, whichare depicted in the circuit diagram of FIG. 27.

Further, the flat cable type high-frequency diplexer 90 of the presentpreferred embodiment can connect, for example, the antenna board 991 andthe front end board 990 using a mount mode similar to the one depictedin FIG. 28.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. A signal transmission cable with band-eliminationfilter functionality, comprising: a signal transmission line thatconnects a first external connection terminal and a second externalconnection terminal; a flexible flat base body in which the signaltransmission line is defined by a conductor pattern; and aband-elimination filter that is connected between the first externalconnection terminal and the second external connection terminal by thesignal transmission line and includes an inductor and a capacitorprovided in or on the flexible flat base body.
 2. The signaltransmission cable with band-elimination filter functionality accordingto claim 1, wherein the base body includes a multilayer structureincluding a stack of a plurality of base layers; the inductor includes aline conductor pattern on at least one layer of the plurality of baselayers; and the inductor and the capacitor are connected in parallel bythe conductor pattern.
 3. The signal transmission cable withband-elimination filter functionality according to claim 2, wherein thecapacitor includes flat conductor patterns located on the plurality ofbase layers and opposing to each other in a stacking direction of themultilayer structure.
 4. The signal transmission cable withband-elimination filter functionality according to claim 2, wherein thecapacitor is a surface mount element; and the surface mount element isarranged at a location where the signal transmission line is cut in sucha way that the surface mount element is connected in series betweenseparated signal transmission lines.
 5. The signal transmission cablewith band-elimination filter functionality according to claim 2, furthercomprising: a series resonance inductor that includes a line conductorpattern on the plurality of base layers and is connected in series tothe capacitor.
 6. The signal transmission cable with band-eliminationfilter functionality according to claim 5, wherein on each base layer, afirst line conductor pattern constituting the inductor and a second lineconductor pattern constituting the series resonance inductor isprovided; the first line conductor patterns on respective base layersare connected by an interlayer-connector conductor; the second lineconductor patterns on respective base layers are connected by aninterlayer-connector conductor; and the second line conductor pattern isdivided into a first portion connecting to the first external connectionterminal and a second portion connecting to the second externalconnection terminal, and the first portion of the second line conductorpattern on a first base layer is arranged opposite to the second portionof the second line conductor pattern on a second base layer over thebase layer.
 7. The signal transmission cable with band-eliminationfilter functionality according to claim 6, wherein the first lineconductor pattern and the second line conductor pattern are provided onthree base layers or more; and a plurality of opposing portions of thefirst portion and the second portion are provided.
 8. The signaltransmission cable with band-elimination filter functionality accordingto claim 5, wherein the inductor includes a first spiral conductorpattern including line conductor patterns and an interlayer-connectorconductor connecting the line conductor patterns, each line conductorpattern being provided in a respective layer of a plurality of the baselayers and including a loop-shaped portion of which is cut off; and theseries resonance inductor includes a second spiral conductor patternincluding line conductor patterns and an interlayer-connector conductorconnecting the line conductor patterns, each line conductor patternbeing provided on a respective layer of a plurality of the base layersthat is different from the plurality of the base layers at which theinductor is provided and including a loop-shaped portion of which is cutoff.
 9. The signal transmission cable with band-elimination filterfunctionality according to claim 8, wherein a winding direction of thefirst spiral conductor pattern is opposite to a winding direction of thesecond spiral conductor pattern.
 10. The signal transmission cable withband-elimination filter functionality according to claim 1, wherein theflexible flat base body includes liquid crystal polymer.
 11. The signaltransmission cable with band-elimination filter functionality accordingto claim 1, wherein the flexible flat base body includes a bent portionbetween a position of the first external connection terminal and aposition of the second external connection terminal.
 12. The signaltransmission cable with band-elimination filter functionality accordingto claim 1, wherein the first external connection terminal and thesecond external connection terminal each include a connector member thatestablishes an electrical connection with an external circuit byconnecting each other mechanically.
 13. A communication device modulecomprising: a signal transmission cable with band-elimination filterfunctionality according to claim 1; an antenna board connected to thefirst external connection terminal; and a front end board connected tothe second external connection terminal.
 14. A communication devicemodule comprising: a signal transmission cable with band-eliminationfilter functionality according to claim 2; an antenna board connected tothe first external connection terminal; and a front end board connectedto the second external connection terminal.
 15. A communication devicemodule comprising: a signal transmission cable with band-eliminationfilter functionality according to claim 3; an antenna board connected tothe first external connection terminal; and a front end board connectedto the second external connection terminal.
 16. A communication devicemodule comprising: a signal transmission cable with band-eliminationfilter functionality according to claim 4; an antenna board connected tothe first external connection terminal; and a front end board connectedto the second external connection terminal.
 17. A communication devicemodule comprising: a signal transmission cable with band-eliminationfilter functionality according to claim 5; an antenna board connected tothe first external connection terminal; and a front end board connectedto the second external connection terminal.
 18. A communication devicemodule comprising: a signal transmission cable with band-eliminationfilter functionality according to claim 6; an antenna board connected tothe first external connection terminal; and a front end board connectedto the second external connection terminal.
 19. A signal transmissioncable with diplexer functionality, comprising: a signal transmissioncable with band-elimination filter functionality according to claim 1;and a bandpass filter including another conductor pattern provided inthe flexible flat base body.
 20. A communication device modulecomprising: a signal transmission cable with diplexer functionalityaccording to claim 19; and an antenna board and a front end board thatare connected by the signal transmission cable with diplexerfunctionality.